There are plenty of sites to keep a freerolling poker player busy. The one they choose depends on personal preference. And noone said you are by any means restricted to just one site for online freerolling, anyone can enter as many or as little as they like.
Here are a few popular ones to name.
Full Tilt [...]

Five advantages of playing freerolls:
1) Playing poker without risking real money. For more cautious people, freerolls are a great way to play poker without the risk of losing own money. This is also a great way to start building up your online poker bankroll without having to cash real money in. Winning one major freeroll [...]

A freeroll poker tournament is a tournament without an entry fee. Sometimes the prize will be cash, sometimes they will include gifts, prizes, and other incentives. Freerolls can be
a good way for broke players to get some free practice in. A freeroll site ideally provides strategies and advice that will take a player without a [...]