Hors d'oeuvres: Plan on people eating between 4 to 8 if your cheap and not serving dessert after the meal. If you decide to be Daddy Warbucks and splurge on dessert, then plan on about 4 per person.
Drinks (the stronger the better): Plan on 3 to 4 drinks in a 2 to 3 hour time frame, that is, of course, if you aren't attending a kegger at your local frat house!
Glasses: Plan on approximately 3 to 4 glasses per person. People get lazy or just too drunk and loose track of where they put their damn glass! You can imagine you could spend all night washing glasses or you can come up with some creative ways for each of your guests to identify his or her glass. For example, hand each person a sticker as they arrive and ask them to stick it on their glass.
Ice: Plan on 1 pound per person. You'll need keep bottles chilled and guest will need it in their glasses.