OK, NO2 (NOX2, Nitrix etc...don't purchase the GNC brand, too expensive) is a hemodilator, which means you get more blood, oxygen and growth nutrients to your muscles. I think it has promise, but I haven't tried it yet. DO NOT take stimulants/fat burners if you want to get big...your metabolism is crazy anyways. Perchul is right, glutamine is usually in powder form (at least it's the most cost efficient variety) and it's good for keeping your body from 'eating' your muscles.
Diet-wize, for calories salads don't count. Too light on calories (if it's a healthy salad). Stick to huge turkey sandwiches, eggs, potatos...whatever quality stuff is in your college dining hall. I would also seriously add a couple of meals per day and drink a meal replacement prior to bed (or eat a meal), so you don't lose muscle at night. If you can, drink a protein shake in the middle of the night. I would also drink a protein shake with some carbs about 45 minutes before lifting (if you can without getting sick). I think the name of your game is going to be try to never go more than 3 hours without eating and never let yourself get hungry. Also, creatine is for recovery and pushing out the extra couple of reps, so I wouldn't use it until you're getting enough calories, otherwise it won't help too much. Get some flax seed oil and take 2-3 tablespoons per day (it's good for you and you'll need the calories...one of the most ripped guys I know takes 4 per day).
Training-wise, like most have said...stay away from machines and use free weights. Focus on compound exercises like bench (with bar and dumbells), squat, military, 1 arm rows etc. Don't go crazy with the reps...8-10 is optimal for muscle growth. Handle the most weight you can SAFELY handle and perform quality reps with a couple cheat reps on you last set. Like previously stated, once per week per bodypart is enough, or you'll be overtraining...you grow while resting, not lifting. Also, squat on Mondays and Thursdays before any other exercises. Your body will release the most testosterone and GH with this exercise. A study showed that guys that did only squats 3 times per week for 6 months gained 1/2 inch on their arms without directly exercising them. Squats hit your whole body and you'll be amazed at the results. Try to fit in deadlifts, too. Get someone to show you how to do them properly.
Finally, before I shut up, rest, rest and then rest. You won't grow if you don't get enough sleep. Try for 7-9 hours and if you have to take a nap to get that much, then do it. That's when your body will grow, so don't neglect it! You've gotten some great advice, so implement a good program and let us know about your results.
JR