Not that all of these things apply specifically to college life - most can be applied to "normal" life so may be worth reading.
If you've something to contribute, please post a reply and I'll add it to the list. This is more of a work in progress as I find new ways to save money at odd intervals.
Step 1: Transportation
Not like you won't being doing enough of this between classes, but walking to other places is a great way to save money. Gas is hovering around $3.80 a gallon as I write this whereas walking only costs as much as the food you run on. If you live in a city where everything is fairly close together, you can most likely get away with walking for 95% of your travel.
Most (if not all) forms of mass transit within cities (buses, subways, etc.) give student discounts. If you use mass transit frequently enough, buy a monthly pass. There might even be a bus or train that runs between your school and your hometown. I can take the Coach bus home from college for $1.25 one way (about a 40 mile drive).
You can also buy a bicycle (or salvage one, if you're savvy enough). Costs for that are only maintenance-related and I don't know a university that doesn't have a bike rack outside every campus building.
If you have to use a motorized vehicle, try to limit it to something small like a moped or a motorcycle. Not only do they get great mileage but most colleges offer discounted (or free!) parking for such vehicles. If you have to use a car, try to carpool. And, if possible, drive a car that gets good mileage (I know, if you're as broke as me you probably can't afford one!)
Step 2: Housing
Most people don't enjoy dorm living (as compared to an apartment). However, it might actually be less costly to live in a dormitory, depending on your situation. Some colleges require you to live on-campus for so many years anyway. Also, most colleges have Resident Assistant/Advisor positions available which you can most likely sign up for after your freshman year. As payment for being an RA you will probably get free housing and food.
Depending on where/how you want to live, you can probably spend less living in an apartment than in the dorms. For example, in Milwaukee (where I go to school), most of my friends pay about $400 a month for rent. Dorms cost roughly $500-$800 a month when you figure it all out, so you can see the advantage of an apartment.
If you're within driving range of your school, you might consider commuting. Yes, you'd have to drive to school every day but you can avoid housing and food costs by living at home.
Step 3: Food
Many colleges offer a meal plan for dorm living, usually with different levels. You know how you eat better than anyone else so choose accordingly. Yes, it'll probably cost more than making food yourself, but that frees up time in your day to do other things.
If you do have to cook (no meal plan options, or you're off-campus) try to spend as little as possible on food. This might sound ridiculously obvious but I know plenty of people who spend more than they have to. For example, you can buy non-name brand items for a good discount off of the better known brands and the taste is usually comparable. Also, instead of buying pre-made meals, learn to cook and make your own. Once you're good enough at cooking you'll enjoy what you make more than pre-made stuff anyway.
improbable1 suggested using a Nalgene or similar bottle and carrying a bottle full of tap water with you instead of buying the bottled stuff. I have to agree on this one.
There's really no way to cut this cost except not to do it. Sometimes you just need takeout.
Be on the lookout for campus events with free food. My college usually has quite a few per quarter and it's hard to argue with free. Stock up if you can.
Depending on how much you drink, alcohol can be a significant expense. The obvious answer is not to drink, but, of course, this is not always possible ;-)
Someone was kind enough to tell me about Eating on $3 a Day, another Instructable.
Step 4: Laundry
Do you really need to wash the pair of pants you wore for one day? Probably not. In fact, you can probably get away with wearing them three or more times before they start getting funky. Same goes to shirts you wear over an undershirt or hooded sweatshirts. Socks and underwear you'll probably want to wash after one use though ;-)
If it's warm enough, avoid using socks entirely by wearing sandals. Then watch your foot turn into a huge callus...
Use cold water
If you use cold water when washing, not only will your clothes not shrink, but you can also mix colors with whites without too much fear of having color bleed. Unless you're religious about your clothes I'd suggest this. That way you can use only one washer instead of two if it all fits in one.
If you play a school-sanctioned sport, chances are they have some sort of laundry system at your recreational facility. If you play a sport you'll probably figure out sooner or later if this is the case. If so, use it to do some of your normal laundry! Usually the employees are students and they don't care what they throw in the washers. I've put jeans on my laundry bag and they've still washed them.
I just saw another Instructable about building a clothesline in your room, which only costs you money once and will end up paying for itself soon. Find it here.
Step 5: Studies
Chances are that you go to a school with a public printer. Chances are that plenty of people use that printer and forget to retrieve what they printed. This usually gets offloaded to a bin nearby. A friend of mine takes the misprints, three-hole punches them, and uses them for class notes in a binder. Not only is it a free notebook, but it saves that paper from going completely to waste.
I usually buy a five-subject notebook at the beginning of the year and use one section for each of my classes. I take sparse enough notes where this notebook can last me the entire school year. If you do take this route, make sure to get one that's durable enough (plastic cover, metal binding with a cloth binding cover, and plastic dividers. Also, if you have pages left at the end of the year, tear them out for later notes/scratchpaper. However, if you take copious notes, you're probably going to want something different.
One word: Refills. Buy refillable mechanical pencils and pens instead of buying the cheapie disposables. (Chances are you can probably find some cheap free ones at campus events, career fairs, and the like). I somehow managed to keep one (ONE) mechanical pencil all through high school and up until the beginning of sophomore year of college before it broke. Also, not only do the mechanicals last longer, but they're just better utensils in general. Quality is key.
Step 6: Other
If you can, mooch off your parents. Chances are if they haven't seen you in a while they won't be averse to buying you some lunch or doing your laundry. They probably miss having you around and having to take care of you (can't promise this though).
Earlier this school year I bought a set of hair clippers (a good Wahl set will set you back about $40). My reasoning is that I can pay $15 every couple months (or more) for a haircut, or I can have one of my friends give me one for free. And I also cut my friends' hair if they want. The clippers pay for themselves with like three uses on yourself - a good investment in my book.