I go through phases of what I like. Some of my favorites (that I rotate between) are: string cheese, salted popcorn, dried fruit, cheese and crackers, ice cream, cookies and milk (especially Double Stuff Oreos). Or basically, whatever is available. LOL
Considering I stay up all night pretty much every night I do usually have a little snack around 3 AM (but don't go to bed until about 11...so it's not too horrible).
I like small, bite sized things...especially grapes or those little grape tomatoes. If dinner was really light though I'll sometimes have a pb&j or one of those instant lunch noodle cups.