PokerTime is on the Prima network. They offer $50 free for signing up (no deposit required) plus up to $600 in deposit bonuses. You can get full details at the PokerTime web site: Download Pokertime
Eurolinx has been amazingly generous with the fast-clearing bonuses lately. In addition to a 100% up to $250 signup bonus, they're handing out monthly bonuses that clear at six points per dollar of poker bonus money, with each hand of poker you play generating up to 1.5 points! Right now, this is the hottest deal on the Internet. And the customer service people are the best I've ever seen at an online poker room.
Full Tilt Poker offers a large signup deposit bonus (100% up to $650) and excellent software. They have tons of players, so finding a game is never difficult. They've been running a variety of different promotions lately, so click the link for more info about their current offers.