The stakes may be high if you choose to play a game of chance on your college campus. Gambling laws vary widely from state to state, and with the explosion in the popularity of poker games like Texas Hold 'em, more and more state legislatures are moving to regulate these games. The likelihood of your being prosecuted for gambling with a group of friends in a casual dorm-room game is remote — but such a game can get you into hot water with the administration, particularly if it gets big and one of the perennial losers complains to a dean about how you took his financial aid money in a poker game.
Things get considerably dicier if you start staging regular poker games, tournaments, or other such events out of your suite or fraternity or sorority house. If you do this, some states may consider you to be running an unregulated gambling hall. Stories abound of these "home games" getting raided by the local police, and people have been prosecuted for it. In many other states, the issue's unresolved as to whether poker is a game of chance (subject to gambling regulations) or a game of skill. Best you let the "entrepreneurial" types run the on-campus games and take this risk — at least until the still-developing laws in this area become more reliable.
Booking sports bets is a clear violation of state law in most states, and being the campus "bookie" can get you into all sorts of trouble, with both your administration and local and state law enforcement agencies. This one is a clear no-no.
As for Internet gaming — again, state laws are widely disparate in this area, and Congress has not yet figured out what to do with this billion-dollar, largely unregulated industry. Many people gamble on the Internet these days with little concern over getting discovered, being held accountable, and ultimately, being prosecuted — but you are responsible for monitoring changes in the law as it develops. If you connect to the Internet through your college IP connection and transfer money to gambling accounts from your checking account through mechanisms like PayPal, FirePay, or Neteller, understand that your activities can be tracked.