recipes for leftover egg whites besides angel food cake

Easiest way I found to use all those egg whites? A classic omelette or casserole. You can also use it as a binder for patties

I like to make delicious cocktails, specifically this one:
The Clover Club:
3 ounces gin
1 ounce fresh lemon juice
1/4 ounce Grenadine or cherry syrup
Egg white

Marshmallow creme for fluffernutters.

In addition to all the other suggestions (I'd probably make macaroons for Passover right now) I use egg whites to bind my turkey burgers.

A couple more savory suggestions: a classic consomme, or a salt crust for baking meat or fish. If I only have one or two egg whites, I use them in a cocktail like a pisco sour.

There are a number of ideas here -- http://food52.com/blog/8086-the-best-uses-for-extra-egg-whites -- both in the post itself and in the comments!

For more incidental usage, if I just have a couple of whites, I've often used them for breading, instead of whole eggs (flour/egg/breadcrumbs.) Also, a single white can be used to brush on a graham cracker or cookie crumb pie crust and pre-baked to stop soggy-ness when filled.

Egg white omelette with scallions is mighty good.

Egg white omelettes, if you want something savory. If you put eggs in your meatballs, I bet just the whites would bind just as well as whole eggs.

Meringues and macarons, seven minute frosting would be my favorites. Always wanted to try Floating Island, which uses poached meringues instead of baked.

Many many recipes use egg whites as a basis for their stabilization. You may also freeze egg whited for a later purpose. Recipes that employ large amounts of egg whites:
Financiere, Meringue, Pavlova, French/Swiss/Italian buttercream, Marshmallows, Royal Icing, Souffle, Macaron, Macaroon, Dacquoise, and they're good for treating burns. Have fun!

A roulade! Chocolate are my favorite. Here's Jacques & Julia's, which calls for 7 egg whites, http://www.marthastewart.com/335600/julia-and-jacquess-chocolate-roulade