For you degenerate blackjack monkeys out there, there's a group of casinos owned by SportingBet offering some pretty nice cashable blackjack bonuses right now, just for downloading their casino. Here's the list, followed by basic details:
1) SportingbetUSA.com: $50 free for downloading casino
2) PlayersOnly.com: $50 free for downloading casino
3) Superbook.com: up to $30 free for downloading casino
4) Aces.com: $50 free for downloading casino
To get the bonus, download the casino at each site, create an account and deposit a minimum of $50. Then you have to wager a total of $10. Within 48-72 hours (and they usually take the full amount of time to give you the bonus, so don't freak out if it takes a day or two to show up), they'll automatically credit your account with the bonus. They don't notify you by email, the bonus is just inserted into your account.
To withdraw the bonus, you have to wager 20xb (1000 WR for the $50 bonuses). What's nice is that the software is lightning fast if you increase the speed, so it's very easy to grind through the WR playing BJ with minimum sized bets.
If you're going to do these you might hurry, as these bonuses appear to be a one-time sort of deal, as an incentive to get players to try out the downloadable casinos.
If you play poker, all of the above sites also offer poker bonuses, so you can hit the casino side first for the bonus, then bang out some raked hands on the poker side to get the $20 bonuses they offer for playing 200-250 raked hands. Not the greatest poker bonuses, but free money is free money.