Anything else that's usually negotiable? That's what I can think of for now.
Just about anything that costs over $100 is negotiable. You just have to know who to ask and how. Some things don't have enough markup to haggle over (good luck negotiating a deal on a PS2), but if you have a good working relationship with the vendor, and he isn't going to lose money on the deal, it can be done.
I usually don't have the guts to haggle with normal vendors, but at work, I haggle with vendors as often as possible.