There's some good advice here (among with some clearly biased views).
Before you just up and enlist in the Marines, I'd make sure you check out all your options for military service. There are a variety of ways to do it. You can straight up enlist (where they DO pay for college when you get out), you can do reserves (where you pay for college and they pay you back as you go) or you can do college first and either do ROTC while in school (which I think gets you some funds while you're in school, but I don't know for sure how this program works) or you can do school and then OCS (Officer Candididate School) when you're done (here they pay off loans for you and you can receive money for graduate degrees - which depending on which branch may be required if you want to make a career out of the military).
If you don't plan to make the military your career - I wouldn't recommend you bother with the officer options.
If it's just a way to get some cash for school - I'd be hesitant before signing up. It requires a lot of commitment to get that funding and there are other ways to get funding (grants, loans, scholarships, Americorps, Peace Corps, employment that offers education assistance, etc.).
If you are floundering, don't think you're quite ready for college, need some discipline and/or direction in your life, you might want to give the military some serious consideration. I know a number of guys who have served, or are serving, and most consider it an invaluable experience.
When considering it though, also consider what you might want to do with you life. If you're interested in persuing some sort of tech field job, you might be better off in the Air Force or Navy than Marines or Army. It's not that the Marines or Army aren't high tech as well; it's just that right now the Army and Marines need fighting bodies so you're more likely to sent to that (unless you have some special skills/training going in), whereas in the other two you're more likely to be able to on-the-job training in technical fields earlier on. Contrary to what you may be told, you don't get to choose whatever job path you want once you're in.
Also, if you're interested in the Marines, I suggest you talk to the poster USMC here on the Hype!. He can give you realistic advice having been in.