There are numerous affiliates out there (I ain't mentioning them here out of courtesy to the board owners, who are also most likely affiliates of many of these sites) who offer the "free bankroll" deals. Off the top of my head, you can get at least $20 n/d at these sites through certain affiliates:
CD Poker, Titan Poker
, Party Poker
, Poker.com, Carlos Poker.
Without having to go through affiliates, these sites after n/d deals for new players: Crazy Vegas, PokerTime & Dream Poker (all Prima skins), as well as Pitbull Poker & Victor Chandler offer $10 n/d to new players, Purple Lounge offers $3 n/d, Stetson Poker offers $25 (but almost no players), i4poker.com offers 5 Euro....and I'm sure I'm missing a few out there.
Playing freerolls is fine, but here's another alternative...plus you get to try out some new sites, in the process