Carbon poker holds freerolls daily. They hold some $500 and some $1,000 freerolls. There are 9 each day with a $200 prize pool. There are additional smaller prize pool freerolls throughout the day.
Bovada poker holds freerolls daily. They have daily $300 and $500 freerolls. You also earn poker points for time spent playing on the site which can be used to enter real money tournaments
BetOnline poker offers daily freerolls 24/7. They have one $200 and three $100 freerolls daily. Additional smaller payout freerolls go on throughout the day.