My advice, is a little different from the rest. All those things are good and all, but it doesn't hurt to lay the ground work for your future.
I recommend that you start coding your statup now. This is the best time for it. You have no expenses. You have very few commitments. And you are surrounded by a lot of other smart ambitious people that you can tap. Clubs, professors, classes, will make it easy for you to find out who the smart people are. So if you run into a problem, you can easily find someone to help you understand it.
And this way the times when your startup grows very slow, you'll have some other things to play with. Honestly if you don't have an idea now, start throwing some ideas in your head, pick one and start coding, if you change your mind along the way, change your product, you have plenty of time to get a winning combination. And remember, it doesn't need to be rocket science, Facebook is nothing more than a big database.
But this shouldn't be your only concern, you have to multi-task. Honestly the startup life is pretty shitty. You work all the time, you lose touch with most of your friends because you constantly skip going out, and unlike college where you are surrounded by women of your age, you end up being pretty much a monk, seeing two-three women your age during the week. So spend that time in college having fun.
a) start lifting weights. Trust me, it'll do wonders to your social life and for your self esteem. Honestly if you are afraid of going to the gym, buy a set of weights at a store and workout at home. I actually prefer that because you don't spend the extra time of driving to the gym, and can do it whenever you have free time.(i usually work out when I watch TV since I'm in front of it anyways)
b) Join some activity clubs. Honestly you sound like you have no idea what fun things you like. So look at all the clubs at your college and join a bunch and see what you actually like.
c) if you want excitement there is nothing better than buying a motorcycle. Start off with a Ninja 250(used). The reason is that its a starter bike(it'll run you like 2K used, 3K new, they hold their value really well). Granted its a little dangerous but thats part of the excitement. Then once you get the basics down, upgrade to a 600cc bike(the most expensive one will run you like 7 grand). And don't upgrade to a 1000cc bike because those are the killers.
d) get laid, Honestly college is probably the easiest time of your life for that .You are surrounded by women your age and as long as you are even remotely in shape you'll get a positive answer. If you wear glasses get contacts. Don't fool yourself into thinking that you'll be knee deep in women once you graduate. Like I said, w/o going out I see maybe 1-2 attractive women my age. And if you hate the party scene in college, you'll hate the bar/club scene when you graduate. You don't want to end up like that guy in the 40 year old virgin movie. And trust me, if you ride a bike, have a decent physique and no glasses, in college? You will have NO problem getting women's numbers. All you have to do is initiate the conversation.
e) take a road trip, just get into your car and head some place 2000 miles away.
f) obviously there are many other exciting things to do, but I don't know your money/location situation, so I dunno if you can afford to go sky diving, or if you live near an ocean so you can learn how to surf/ride a jet ski