I'm a Delta Zeta in MI, and our chapter has had great crush parties....
Here are some ideas:
"Partners in Crime"- HANDCUFFS. You are handcuffed to your date. You have a pre-party and you do a shot together to get the cuffs on. Sounds not so great, but it was a blast!!! It's also great for t-shirts...we had really cute ones!
"Mystery Date"- Each bro. or sis makes a list of 5 people. Another bro or sis picks the one who will be their date but doesn't tell them. You have 2 pre-parties...the girls wear the boys' ties. After pre-partying, you meet up in a big group and find the girl with your tie on. It was fun also.
These may not seem really original, but they were a blast!