There are some websites that'll pay you to fill out surveys.
If you're a college student, besides the rent idea (read some of the real investment books as they'll point out some issues/laws you need to be aware of when doing this), you can also donate plasma to make some money. Plasma centers may offer up to $60 for the first visit, and then it lowers with each consecutive visit until a certain point (say $20 or $30/visit).
The most legit online money making method is to buy/sell stocks online. Do some research into the best online trading firm for the best rates that'll suit your needs. Some offer a flat rate, while others offer a declining rate for the amount of volume, or value, of trades.
Second Life and Entropia Online are two "games" you could try to make some money from.
BitCoin is another. Believe there is a thread in the Tech section about this.
Selling stuff online via eBay and being paid via Paypal. Through college, I kept an eye out for large discounts on popular items. My RA did the same thing; bought four cameras for about $85 apiece, and resold them for $130 on eBay. $45 profit times 4 = $180 less S&H and a few hours to setup the auction, and prepare to ship.