Hoy!
Here's a coupla ideas
) Take your overhead projector open it up and put a little DVD player inside playing loop - maybe tilt the player so that its plane is not perpendicular to the proj glass so that the focus is slightly different from side to side of the image / make sure it shows in the top glass / unfocus the projector head so that the image playing is not recognizable. Never tried this - just an idea
)Rent an orthographic projector which lets you blow up images laid on its table. Put your DVD player down there / project onto stage. This method has limited size and brightness, but if you put it on the stage it might work. Never tried this either...
)Borrow a 16mm proj and the oldest films they have from a school / smear vaseline on the lens - or unscrew the lens or defocus the lens for mysteriousness / project films onto stage and whatever they happen to hit. You might have a friend help with this one. This I have done although using 1000 foot reels and several projectors (and several friends). Old science films and cartoons etc can go abstract really cool! The clacking of the projectors is also a very cool rhythmic sound (with several you get polyrhythms) that you can work with.
)Save the best for last. Mix giant batch of Sangria (red wine with cut up fruit in it) mix in about 200 hits of acid. Serve to every guest - miss no one! Seconds are OK if everyone has had at least one cup. Turn off all the lights except for tiny worklights and play show. Guaranteed memorable evening.
If I think or hear of any other cheap and easy ideas I'll post more later
Otherwise, good luck!