Apartment Summer Party - Minute To Win It! Hot
While games are fun, I suggest some Ice Breakers. An important thing is to incorporate an introduction into the game. Have people introduce themselves every time they go up to a new person. That is what is going to get people socializing and meeting new friends, more so than music, games, food, etc. There are lots of books and online resources to find some fun Ice Breakers, but make sure they last at least 20 minutes so people get a chance to meet others. Statistics show that the more friends people make in their community, the more likely they are to renew their lease.
As for prizes, check out the daily deals websites like LivingSocial.com for half price gift certificates to local restaurants, adventures and such.
Lots of fun, just practice first
I LOVE this as an apartment party. We actually set this up as part of my brother's bachelor party and had a great time. Keep in mind - they need to be tested to get the kinks out before game day. Other than that, it's a VERY inexpensive resident event!