If you can't find anything you like online, I'd suggest browsing through Indian cookbooks at the library/book store.

I love the cookbook 'Indian Home Cooking' by Suvir Saran. He has some great drinks - including lassis, chai teas and a sparkling ginger limeade (which is my favorite to serve to guests as it's very pretty!)

A great drink that my mom (Indian) always had on hand during the summer was sweetened fennel water. Just add fennel seeds and sugar to boiling water. Boil for a couple of minutes, turn off the heat, and allow the fennel "tea" to steep until it has come to room temperature. Filter out the seeds now, or when you're ready to prep a drink. I usually make this the consistency of simple syrup, which leaves me the option of adding it to alcohol (rum or vodka are good) or to iced water for a non-alcoholic drink. It's a wonderfully refreshing drink on a hot day. Throw in a sprig of mint and I think you'll have a real winner. Good luck with your party!

How about a pitcher of Pimm's Cup? Very British Colonial era, but also very refreshing with a spear of cucumber and a plate of spicy food.

One refreshing drink I had while traveling in India was watermelon juice. It's as simple as it sounds and better for pouring than lassi.

Pimms is a great idea...as is the fennel syrup as an addition to a martini. I was going to say two things. One, I like to drink Sauvignon Blanc when I eat Indian, so maybe you could fine a good SB-based punch recipe. Punch=party. Or, I think orange and cardamom taste good together. So you could try a pitcher of blood orange cosmos with a little hint of cardamom.

Around here there's a very sizable recent-immigrant Indian population, and at restaurants they usually set a pitcher of cool (no ice) tap water on the table and that's what people drink during the meal. There's also hot chai, and Indian beers (Kingfisher comes to mind). Hot chai can be cooled and iced, but that way of serving it is not "authentic" if that's what you're going for.

I know that's not very exciting. Maybe you could veer into the colonial palette with IPA or gin-based iced cocktail. Or maybe go totally wild and make up something sort of "Indian-inspired" like a cocktail with notes of mango (Absolut makes a mango vodka), coconut, mint, tamarind, etc.

I immediately thought along the same British Colonial lines as CLou and thought of a G&T. Get a good British Gin and you're good to go.

You could also serve up Tiger Beer. (I think that's the one from India) It also goes well with Spicy foods and shouldnt be impossible to track down.

Last idea: Serve up a number of IPA's. They're great summer sinks and theres a good variety at the moment since they've gotten trendier.

<blockquote>Maybe you could veer into the colonial palette with IPA or gin-based iced cocktail.</blockquote>

That is, an IPA beer OR a gin-based cocktail. As opposed to an IPA-based cocktail, which sounds like a recipe for barf-o-rama.

A pitcher of cucumber water or coconut water might be a nice, simple way to go. Lassi is very stereotypically Indian, but it might be difficult to keep out in large quantities, and it is very filling.

Since alcohol isn't very popular in India (both Hindu and Islam frown on it), there aren't any native Indian cocktails, so your best bet may be to invent something with the flavors of India, like mango, tamarind, chai, and ginger, or opt for the drinks of British colonialism, such as gin and tonic.

Sounds like a fun party!

Nimbu Pani! It is the Indian version of lemonade :) Nimbu Pani w/ fresh berries

Madhur Jaffrey has a nice ginger limeade in her World of the East vegetarian cookbook. You could probably just do it w/o the recipe -- the key is grating the ginger and squeezing the juice into the limade.

As mentioned, alcohol isn't particularly traditional, so if you really want it you'll have to improvise.

You could infuse vodka with Chai spices (cardamom, cinnamon, ginger, fennel seeds, peppercorn, and cloves etc) and/or tea. Serve chilled as a martini.

I've seen several brands of Indian sodas available, so you could do a rum and coke with one of the colas.

Otherwise, mango lassi is the best thing in the world on a hot day.

You can make chai or cardamom tea. I'd imagine that cardamom tea would be a great base for ice tea, with cardamom having kind of a cooling taste. Also look up thandai.

Almond sherbet is also good.

What a fun question!
I expected to see lassi on the comments here and I did :) The thing about it though is that it really is quite filling, even more so if it's mango. I'd go with chaas (salted buttermilk) if I was going down this route. Here's one recipe
http://indianfood.about.com/od/drinkrecipes/r/masalachaas.htm
I second the comments here about water. That's really what we consume with our meals. Chai (our traditional tea) is actually served mostly with breakfast or at tea time. (I know every Indian restaurant in the US serves it at any time so it's really up to you). Hot, not cold.
I also second the coconut water and nimbu pani suggestions, also the watermelon juice, all are light and complement the food very well. Add a pinch of kala namak (black salt) to the lemon or watermelon juice and you're all set.
We love sharbat (cool flavoured syrup drinks) and lemon and orange squash, all available at your friendly, neighbourhood Indian store. Look for a cooling drink called Rooh Afza. (http://en.wikipedia.org/wiki/Rooh_Afza) It's a thick rose coloured syrup you mix with water that makes for very refreshing, herb-y, rose-y drink. Mix in some mint and some neutral flavoured alcohol and you can get a creative cocktail out of it. There'll be other syrup options too so I'd go to the store and look.
Happy planning!

I second the Rooh Afza.

Sparkling limeade with chaat masala--so refreshing. See Neelam Batra's The Indian Vegetarian for the recipe.

Rose essence and saffron were both common additions to Indian sweets my mom used to make when I was a kid. I wonder if either might translate well in a cocktail.

For beer, try a pale ale such as Sierra Nevada or an Indian Pale Ale (IPA). Sierra Nevada, to me, has always had a note of rosewater in it and reminds me of India.

Definitely limeade. I actually like the salty version better than the sweet.

Someone above mentioned Tiger Beer --- sorry, that's not typical Indian tipple! You'd be tracking down a Kingfisher or Haywards 5000 or similar, if you wanted to go 'native'.

I don't know if it's possible to get raw (green) mangoes where you live, but if you can, it can be boiled or baked till soft, and the pulp used to flavour a drink either alcoholic or non-alcoholic. The favourite flavouring is cumin --- roasted and powdered, along with sugar to balance the mangoes' tartness. Add vodka or white rum for a mixer, or just served iced for the virgin version.

Other spice choices are cardamom seeds, crushed in; a tiny pinch of chilli and salt; fennel seeds; or black salt (kala namak, at the Indian grocery); or even 'chaat masala' if you can get it. Or just add chopped mint.

If you can't get hold of the mangoes, check at any Indian stores nearby for bottled 'Aam panna' (spelling may vary a bit; suggest asking for a green mango drink). It's usually a bright green concentrate you water down.

Alternatively, try this with pineapple juice.

Another option is a tamarind-based cocktail. You add simple syrup to tamarind juice (you can buy it packaged, or make your own if you can get hold of tamarind pods by soaking in warm water, and then removing the seeds and tough fibres --- whizz in a blender for uniform texture). We'd usually add mango powder ('amchur') if it was the 'sweeter' (read: not exactly tooth-souring) Thai tamarind. Spice it with a little chilli/pepper (depends on your taste for heat), salt and add a squeeze of lime after watering down to taste. Use as a mixer for vodka. Goes great with Indian snack foods, crisps or poppadum. We also add a concentrated version to a summer potato salad (no cream, sometimes yogurt; chopped onions; some tart fruits diced in; some cooked garbanzo beans).

I've had tamarind margaritas at a sort of nouveau-Indian restaurant. Probably not traditional, but very tasty. I don't know how they made it at the restaurant, but I found this recipe: http://www.foodandwine.com/recipes/tamarind-margarita If you think about it, tamarind margaritas make sense as tamarind is tart, like lime.

I know Heidi Swanson's new book Supernatural Everyday has an Indian drink or two in it. One with ginger that I'm blanking on the name that sounded fabulous..good luck!

what about this recipe from the kitchen itself for gin and tonics with botanicals? you could make a good old colonial g&t bar and set out indian inspired whole spices - cinnamon, cardamom, star anise - to be added. Guests can "clap" their own aromatics before adding to their drinks

http://www.thekitchn.com/thekitchn/gin-and-tonics-4-simple-botanical-twists-straight-up-cocktails-and-spirits-148122

Just thinking of what we make in the summer, a lemonade with orange blossom water and mint in it mixed with gin always goes down a treat? And can be made alcoholic or non-alcoholic with the omission of gin!

Or else maybe something with saffron and cardamom in it? Quite fragrant but delicious and SO beautifully coloured!

The other drink that my mother always made for the ladies/ non-drinkers was something she calls Ladies' Champagne which is chopped up granny smith apples, mint, green apple juice and sprite/7up. Just a thought.

What about tamarind drink?

Another popular summer drink uses a pink rose-water flavored syrup caleld Rooh Hafza http://en.wikipedia.org/wiki/Rooh_Afza

You can usually find it Indian grocery stores and some Middle Eastern stores. It's pretty standard to have it mixed with cold water and a squirt of lime. You can certainly make it with a clear liquor, sparkling soda and a squirt of lime.