I make blueberry frozen yogurt, peach and nectarine sherbet and lavender and meyer lemon low fat ice cream. I haven't tried the Jeni's recipe yet, but I plan to soon!

David Lebovitz's chocolate sorbet tastes incredibly rich, but it's quite low fat. You can see the recipe on Food52 - http://food52.com/blog/3680_david_lebovitzs_chocolate_sorbet

You can make fruity sorbets with just fruit, sugar, and some lemon.

Try frozen yogurts, using 2% Greek yogurt. Creamy and rich tasting! They get a bit rock-hard in the freezer over time though, so go ahead and churn it the day you intend to consume it

Get yourself a copy of The Perfect Scoop. While the ice creams are not low fat, the sorbets and frozen yogurts are incredibly flavorful.

Sorbets- those dairy-free ones have intense flavors. Sherbets in US have dairy.
Gelato- intense flavors in lower fat milks. Italians have made these a high art.
Frozen yogurts/Kulfi's
Frozen Ices/Granitas
I've made some "ice cream" using a low fat pudding mix and 1% milk. Vary the pudding flavor and the mix-ins.
You can try non-custard ice cream recipes, too.
Blogs have tons of recipes for dairy-free, allergy, sugar-free and any other variant you can think of.

You could also try some of your favorite beverages- aguas frescas, horchatas, smoothies, and so on in your new freezer.

links:
basic lemon sorbet
basil or mint sorbet
frozen peach yogurt
spiced apple cider sorbet
ice cream, gelato, sorbet, granita
Patricia Wells' Yogurt Sorbet
Plenty more intriguing options in just the Kitchn's recipes area.

If he's watching his weight, he should be also watching his sugar intake, not just fat. This is a tough challenge because sugar controls the texture of ice cream or any frozen treat, without enough of it, you end up with one very hard and icy frozen treat. The commercial low fat, sugar free ice creams contain a lot of stabilizers and emulsifiers in them, to mimick the texture and mouthfeel of ice cream.

I would recommend having the real thing in a small serving and as an occasional treat rather than making something that falls short of what you like or want on a regular basis.

I was in the same boat. I finally got my ice cream maker and my husband decided to go on a diet. That pretty much killed making ice cream regularly except once or twice a year.

Try these gelato recipes from Saveur:
http://www.saveur.com/article/Recipes/Chocolate-Gelato-
http://www.saveur.com/article/Recipes/Pistachio-Gelato-

I've made the chocolate, and it was really good. It's not sugar-free, but it was very flavorful, so you could probably get away with not overdoing it (and in turn avoiding too much sugar, as ATNIEL commented).

I'm agree with the editor in terms of ice cream without eggs, or Philadelphia style. I started making ice cream this summer and we love to make a Philadelphia style vanilla ice cream where I use half milk/half cream. Also I'd suggest looking at gelato recipes. I liked Ciao Bella's cookbook. They use a ratio of 2:1 milk to cream and a bit less sugar than usual. David Lebovitz is the best. I actually found a terrific chocolate gelato recipe in his "Ready for Dessert" that uses milk only.

I'll add a serving suggestion too.
Use custard cups/ramekins/baking cups to serve your creations. Cereal bowls and ice cream dishes can be larger than you or he realizes. Depending on the brand, one of these custard cups can be 6-10oz.
For him, portion size is as important as the fat and sugar contents. Work out a list of flavors he loves, you love, and any others intriguing to you both. Begin trying recipes with those flavors and that meat his other requests.
Cold can deaden your taste buds, so be ready to boost any wimpy-flavored recipes with more of the main flavor ingredient, if needed.

Thanks for the suggestions! The chocolate sorbet recipe looks amazing (I love DL) and good call on the gelato. My fiance's dessert every night is half a cup of Edy's Slow Churned (he eats it out of a measuring cup--not the cutest bowl in the world, but it really keeps him honest on portion control)--it's this nightly treat that's allowed him to stay on track and lose about 20 lbs. So I want to make something that lets me play with my new toy and lets him enjoy the final product.

That is a great idea about the smaller cups as well. After reading the comment, I got some 6oz Gladware containers and am planning to freeze the churned ice cream in those containers so it's pre-portioned.

I make a high protein nonfat frozen treat that won't really help you with your new wedding gift but it could help your fiance. I mix nonfat vanilla greek yogurt with frozen berries using an immersion blender, roughly 2/3 berries to 1/3 greek yogurt. It's basically taking your favorite smoothie recipe but using frozen fruit and omitting any juice you would normally add, so it ends up all thick and frozen yogurt-y. And I can make it in less than two minutes!!

When I get an ice cream maker, this frozen yogurt will be one of the first things I make! http://smittenkitchen.com/blog/2007/05/pinkcherry/

Weight-wise, I'd be a lot more concerned about the sugar in ice cream than fat in anything.