primedice is the best! you should check it up! you have a free faucet you bet 100 satoshi for free every minute and if you are active you have 1000 satoshi faucet
What is the requirement to withdraw?
You need to make a valid deposit first. I don't know if you have to play with it, but there's some fee involved in sending / withdrawing. So you need to make sure you win quite a lot with the free faucet bitcoins if you wanna make a profit. Read up on the rules at their site.