The best dairyfree version is the chocolate mousse topping Isa Chandra Moskowitz published in her "Vegan Cupcakes take over the world" book.
It is supposed to top cupcakes, but it is also divine eaten by its own. Pure chococolate heaven and easy to make!

Use:
1 package 12.3. ounce firm aseptic silken tofu
1/4 c. plain soy milk (I use a rice and soy mix, or oat milk, as I like it more)
2 tbs. agave syrup
1/2 vanilla bean (scrape down all the vanilla inside the bean; Isa uses 1 tbs vanilla extract, I prefer the real thing)
1 12-ounce package semisweet chocolate chips
(I use chopped solid chocolate bars, I use Ritter Sport)

Chop the chocolate in small pieces. Heat a little bit of the milk untill almost bubbling, remove from the heat and add quickly the chocolate. Stirr to dissolve the chocolate, let it cool untill lukewarm. Puree the rest of the recipe in a blender, bend a lot to get in completly smooth. Mix in the melted chocolate in and bend again, fill in ramkins and chill for 2 hours or longer. Enjoy with a small fruit decoration, some siffed cocao or an edible flower.

Mexican Chocolate Tofu Pudding

3/4 cup sugar

1 pound silken tofu <http://topics.nytimes.com/top/reference/timestopics/subjects/t/tofu/index.html?inline=nyt-classifier>

8 ounces high-quality bittersweet or semisweet chocolate <http://topics.nytimes.com/top/reference/timestopics/subjects/c/chocolate/index.html?inline=nyt-classifier>, melted

1 teaspoon vanilla extract

1 1/2 teaspoons ground cinnamon

1/2 teaspoon chili powder, or more to taste

Chocolate shavings (optional).

1. In a small pot, combine sugar with 3/4 cup water; bring to a boil and cook until sugar is dissolved, stirring occasionally. Cool slightly.

2. Put all ingredients except for chocolate shavings in a blender and purée until completely smooth, stopping machine to scrape down its sides if necessary. Divide among 4 to 6 ramekins and chill for at least 30 minutes. If you like, garnish with chocolate shavings before serving.

this is incredibly delicious. don't tell people about the tofu before they eat it b/c they'll be biased. it's better than dairy based pudding - really.

Raw chocolate mouse made, simply, with avocado, cocoa powder, sweetener (agave works well, or raw sugar), and vanilla. It sounds a bit odd, I'll admit, but its a spectacularly decadent, rich and creamy dessert with nothing to feel guilty about!

I make one that is sooooo easy and usually a huge hit! My recipe is approximate though, so bear with me....

You will use a food processor and a double boiler or a pot on top of a pot with some water in it.

You will need silken tofu and dairy-free semi sweet chocolate chips, vanilla extract, and maple syrup.

I start by melting the chips gently on the stove in the double boiler and adding vanilla. once it is melted i add the maple syrup and this is where it gets weird--the whole thing will turn into a giant fudgy clump and it will freak you out! dont worry. remove the heat and dump the fudgy lump into the food processor with the silken tofu. process till smooth, spatula it into a bowl and chill it (it will be not that solid when you first get it out of the processor and much more solid when you take it out of the fridge)

i would use about half a bag of chocolate chips i think, but it is really up to you. you could also add other flavorings like liquers (chambord, amaretto, etc), orange rind.. i usually bring it to parties with fruit.

hope this helps!

well it's not exactly a mouse, but you may want to try this:

1 avocado, diced
¼ c raw agave nectar, or more to taste
¼ c cocoa powder
¼ c water
2 t vanilla extract
¼ t sea salt
Place avocado, agave nectar, cocoa powder, vanilla extract and sea salt in a blender. Gradually add 1 tablespoon of water at a time to achieve a creamy consistency.

you can use coconut milk instead of water too!

Oh my god, these all sound so good. Does anyone have ideas for a soy, avocado, and chocolate free mousse? Maybe like a vanilla or berry mousse? Soy, avocados, and chocolate all give me migraines. (Makes being vegan tough!)

I tried two recipes:
1) Mexican Chocolate Tofu Pudding (New York Times / Mark Bittman), as TAmom posted. My only advice is add less cinnamon, it could kill the chocolate flavour. And let it rest for 8-12 hours, the consistency changes a lot.

2) Water Chocolate Mousse e Heston Blumenthal's Chocolate Mousse (Video) - Hervé This: yes, only water e really good chocolate. It's more light, but could melt outside the fridge.

Both are great! :)

I was going to recommend this one: http://cafefernando.com/the-best-chocolate-mousse-of-your-life-under-5-minutes/
but realized Vitor beat me to it! Chocolate and water, doesn't get any simpler!

I agree with @vitor and @TAMom. The NY Times recipe is great. I made w/o the cinnamon and chili power, used some vanilla instead. Delish and easy!

I only make non-dairy chocolate mousse, since I'm lactose-intolerant. My favourite recipe is adapted from Nigella Lawson and I posted it here (http://amelieschoice.blogspot.com/2010/06/chocolate-mousse.html); the Kitchn also has a good one made with olive oil (http://www.thekitchn.com/thekitchn/dessert/recipe-chocolate-mousse-with-olive-oil-and-sea-salt-093146), which I top with lavender salt.

Neither one is vegan, but you can buy pasteurized eggs in the shell to make this if you're worried about raw eggs.

chocolate mousse is commonly made without dairy. Here is a recipe from the Cote d' Or chocolate website that is dairy free

http://www.cotedor.be/cotedor/page?siteid=cotedor-prd&locale=befr1&PagecRef=600

for 1 serving: banana (frozen or not, depending what consistency you're going for) + 2 tbsp cocoa + 1T almond butter in the blender.

i got it from green kitchen stories, i think

The Blumenthal mousse beats any dairy mousse I've every tried. I can eat the whole bowl on its own!

I agree Blumenthal is the way to go!

Here's my recipe which is rich and delicious: http://roadtothefarm.blogspot.com/2010/02/coconut-chocolate-mousse.html

Heidi at 101 Cookbooks has this great one: Amaretto-spiked Chocolate Mousse Recipe. It's been a huge hit for me at dinner parties.

My husband is allergic to eggs and poultry, so I had to find a vegan version of chocolate mousse for valentine's day last year. I found a recipe for raw vegan chocolate mousse that was made from avacado. It is amazing.

Raw Vegan Chocolate Mousse

Prep Time: 10 minutes

* 4 Ripe Organic Avocados
* 1 Cup of Sweetener (Agave Nectar or Evaporated Cane Juice)
* 1 Tbls of Pure Vanilla Extract
* 1 Cup of Organic Fair Trade Cocoa Powder (or Carob)

Slice each avocado open and scoop out the insides. Place the inside in a food processor or blender. Next add the sweetener, vanilla, and cocoa powder. Blend or process the mixture until fully blended. The mixture should be smooth and the color of chocolate. You can instantly serve the mousse, however we recommend you let it cool in the fridge for at least an hour. Serve in cups with fresh fruit or mint.

If you don't need it to be vegan, and just want nondairy - ie - this has eggs - , this is the recipe I make- (also from the NYTimes) -
http://www.nytimes.com/2007/03/28/dining/281prex.html?ref=dining
I sometimes put in less olive oil to make it slightly less rich - and often double it for a crowd. I've also served it as a frozen mousse.

I have a pretty straightforward recipe from Cookery—The Australian Way, (the traditional textbook of choice) which I used back in my first year of highschool, and worked quite well (although I believe we just melted it straight in a saucepan, or possibly even the microwave)

Number of serves: 4

Ingredients:
– 4 eggs
– 4 oz. chocolate
– 1 teaspoon water

Method:
1. Place chocolate in top of double saucepan with 1 teaspoon water and slowly melt it. Allow to cool slightly.
2. Separate whites from yolks of eggs.
3. Add egg yolks slowly to the melted and cooled chocolate, stirring all the time.
4. Beat egg whites stiffly and fold them into chocolate mixture.
5. Pour into glass serving bowl, and stand in cool place for 12 hours or more.

Here's a great recipe I make all the time from Cooking Light. I keep kosher so this is a non-dairy version. http://find.myrecipes.com/recipes/recipefinder.dyn?action=displayRecipe&recipe_id=10000001571507
You can also find it by searching on the Cooking Light website for "Chocolate Mousse".

Here is a Great One I just found on Veg Edge

VEGAN CHOCOLATE MOUSSE
IN EDIBLE CHOCLOATE DESSERT CUPS
WITH RASBERRY SAUCE
CHLOE COSCARELLI
Ingredients
Chocolate Cups:
1 1/2 cups semi-sweet chocolate chips (non-dairy)
Chocolate Mousse:
1/2 cup non-dairy milk
1 teaspoon instant espresso powder, optional, preferred for richer chocolate flavor
1 cup non-dairy semi-sweet chocolate chips
1 (13.5-ounce) can coconut milk, chilled
1/2 cup organic powdered sugar
Raspberry Sauce:
1 (12-ounce) bag frozen raspberries or 2 cups fresh raspberries
1/2 cup agave nectar
2 tablespoons water
1 teaspoon fresh lemon juice
1/8 teaspoon salt
Chill the bowl and whisk of a stand mixer in the freezer for 15 minutes.
Directions
For the chocolate cups:
Melt the chocolate over a double boiler until smooth. Line a 12-cup cupcake tray with paper liners and scoop approximately 1 tablespoon melted chocolate into each cup. Use a pastry brush to evenly coat each cupcake liner and paint the chocolate up the sides of each liner, stopping about 1/2-inch/1 cm from the top. Freeze the tray for several hours or overnight. Peel off the cupcake liners and store the chocolate cups in the freezer.
For the chocolate mousse:
In the interim, whisk the milk and espresso in a medium-size saucepan over medium heat. Once the espresso is incorporated, add the chocolate chips and whisk over low heat until the chocolate is melted and smooth. Pour the mixture into a large bowl, let cool, and then chill in the refrigerator until cool to the touch, about 15 minutes.
Scrape the cream from the top of the coconut milk can into the bowl of the chilled stand mixer. Add the powdered sugar and beat for 1 to 2 minutes, until fluffy. Add the cooled chocolate mixture to the stand mixer and beat on low speed until incorporated. Let chill covered, in the refrigerator overnight. Serve the mousse in the chocolate cups.

For the raspberry sauce:
In a medium saucepot cook the raspberries, agave and water over medium heat for about 15 minutes, or until thick and saucy. Remove from the heat and stir in the lemon juice and salt. Let the mixture cool, then store in the refrigerator. Use the sauce to garnish the mousse or the plate!

I haven't tried this yet, but it seems to be chocolate mousse made from equal parts water and chocolate... It looks kinda awesome... But also a bit of work!
http://justcookit.blogspot.com/2009/04/chocolate-mousse.html