One thing I’m surprised people haven’t mentioned is a place setting and utensil set. Nothing fancy, but a plate and bowl will be useful, as well as the fork/knife/spoon thing (however, if you plan on doing any entertaining, a second set is nice). Also a couple of pieces of tupperware (for leftovers, etc.)
Other things people haven’t mentioned: 3-ring hole punch, flashlight, battery-operated alarm clock, calculator, postage stamps and letter-size envelopes, and an extra pillow (dorm ones can be pretty worthless)
Some bigger ticket items listed (curtains, fan, humidifier) as well as some others (answering machine, portable iron) can probably wait until you arrive since it’ll save you space while moving, and they’re costs you can split with roommates (or determine if you need at all–someone else might be bringing them already).
Last of all, you definitely need to bring an open mind. Given that you’re on the SDMB, I doubt this’d be an issue, but as someone who oversaw a dorm of 1000 students, I know the #1 roommate conflict issue I’d see was people coming in with too unrealistic and too rigid expectations of their roommates. Do you know them already? 99% of the time, you don’t, so people who’ve never had to share a room before (say, with a sibling) often come in totally unprepared about what to expect.
Sit down and write a list of things you do/don’t like. Are you a night person or morning? Do you listen to music while studying? Are there certain types of music you absolutely hate? How loud do you listen to music? Are you planning on having sleepover guests? How would you feel if your roommate did (especially if s/he did a lot)? What is your concept of “sharing”? “Privacy”? “Personal space”? How do you relax? Do you drink and do you mind if others do? Are you a talkative person, social and outgoing? How do you deal with someone who is/isn’t?
Being a roommate involves compromising on some of the above, and needing to assert your right to some of the above as well. How are your confrontation skills? Are you passive-agressive? Do you like to avoid conflict? How flexible are you? I’ve seen a lot of first-year students go in expecting to bond with their roommates; it doesn’t always happen. But very different types can get along fine if you actually initiate a conversation about this kind of stuff early on (it doesn’t have to be all serious, but it’s a good way of helping break the ice). You’ll find that your self-assessment skills will go through the wringer at college, but if you take it for what it is–a process that lasts until graduation–you can make the most of it.
I should add one last thing. Dorm Rules. I’ve broken them and I’ve enforced them. One thing I always emphasized to the students I worked around (and lived with) is that with additional freedom comes additional responsibility. Treating them like adults meant holding them accountable like adults. It won’t take more than 10 minutes, so be sure to read what all the dos/don’ts are in your dorm. Some might seem stupid, some might seem obvious, but if there are any that don’t make sense or you disagree with, don’t hesitate in looking up your RA/RD and asking them for the lowdown. You still may not agree, but I often found that certain scenarios never occurred to people before (scenarios that are much better avoided) and they’d come away having a better sense of why some of the rules are there. Also, it’s good to know your hall staff because they’ve been on campus a while, so they’ll have answers to questions and access to resources that could help early on. Plus, if any situation comes up (you get “busted”, you have a problem with your roomie, you need someone to talk to, etc.), you already have a bit of a rapport with that person.
I am certainly not the first person to say that college students very rarely allow school to get in the way of their education while enrolled. Have a ball and good luck with everything. 
and even microwaves aren’t allowed, although a small refrigerator is. I love to eat, and do so 24/7, so a fridge will help, but the no microwave thing sucks.
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