Have someone do just the computer/Internet stuff. We spent *way* too much time trying to arrange for all the Internet connections and set ups.
Each room should have a lectern and a microphone whether they are requested on the order form or not.
People tended to order overhead projectors and flip charts "just in case." This is all right if you're not renting them from the hotel (at exorbitant prices). On the other hand, if you've gone to a lot of trouble to scrounge an extra overhead or flipchart (a rare commodity these days, but much in demand), it's aggravating to have them go unused.
Extra easels are very handy for signs, message boards, etc.