Almost all of them do. I think you need to be more narrow with your question, e.g. does anyone know any site that has frequent freerolls with a small field and no restrictions? Almost any poker site
has some sort of public freeroll happening. Full tilt, Poker Stars (freeroll satellites into a freeroll), Merge Network (Carbon, Poker.com, Walker Poker, Wass Poker, Reefer Poker, Aced), Cake (Player's Only, Sportsbook, Doyle's Room), Ultimate Bet (similar to Poker Stars sats), etc. Pitbull has one every hour with a fairly small playing field, usually around 350-400 players, but the prizes are small. Out of all the ones I mentioned though, it's definitely not easy to make good grinding money. Best bet are joining forums and playing in private freerolls.