I'm with you OP, I'm in Indiana and its maybe 90degrees+ where I am. Our air conditioner went out too late last week. We thought we fixed the problem when DH changed the filters, but then the house went back to being hot. Luckily, we have a basement and that's where we've been camping out at night, but even the basement is warming up.
I do have some suggestions:
1) close as many un-necessary vents as you can, If you are still getting a little bit of cool/cold air
2) Close all your curtains and blinds
3) Here's my favorite part- don't do laundry or dishes even cooking. The heat makes your house hotter
4) During the day find a reason to be in your air conditioned vehicle
5) Hide out at the library or mall or a friend's house as another poster suggested. The grocery store, Target, Wal Mart, are other good places (any place w/ air cond.) to hang out.
6) Take lots of showers or baths to keep you and your baby's body cool.
I hope you get your air fixed soon. I like the other poster's idea of going to a hotel! I'll have to present that idea to my DH. Thanks Aimeedyan!