Dude,
All the CardsChat freerolls are good.
Work your way through this site, reading ALL THE STICKY NOTES and ensuring you read before asking.
My favourites are the country specific weekend freerolls. (These have additional requirements...read to learn about them). Best bang for the buck, IMO. But I enjoy playing with the Canadians, being an ex-pat...so, basically all of the CC freerolls are good.
Keep reading around the site and you'll also come across leagues, special format tourneys, team games, etc. ...each with cash prizes for winners/leader-board players,
Cheers,
ObbleeXY