The kitchen lounge is a good place to eat meals or do work. Hall meetings are held there weekly. The second lounge is more of a reading or small-group meeting area. It has several whiteboards, which useful for problem sets or a rousing game of hangman. The lounge is also home to the hall's computers and printer, which are available for residence use.
Every hall has a tutor suite which is occupied by a graduate student whom the hall selects.
There are scattered storage rooms, which contain nothing interesting unless you like vast piles of extra toilet paper. Other small cubbies appear in the hallway which serve no useful purpose except, perhaps, ambushing passer-bys during water fights. If you're artistically inclined, you can paint murals on the hall walls. Technically, you're supposed to get people to sign a petition to allow the mural. It's probably best that you do this, but everyone likes murals and it's highly unlikely that anyone will oppose one.