Everest Poker is offering a $100 Bonus just for registering with them. No deposit is required.
http://www.everestpoker.com/promo/welcome.html
The site also offers FREE SNG's with $0.10 prize pools.
http://www.everestpoker.com/promo/freeroll.html
They also offer microlimits starting at $0.02/$0.04.
So theoretically, if you don't mind grinding it out at the penny tables for a while, you could build a bankroll at the site without even depositing any money. Just win a few freerolls, then work off that bonus.
The site is only a few months old and originally restricted US players from making deposits because the developers were originally based in the US. The developers were recently bought out by a Taiwanese company though, so I believe the policy has been changed. I had no problems making a deposit with Neteller. I am trying to get a definitive answer on their policy.
Considering the site is fiarly unknown and has practically no US players as of yet, it actually has a decent amount of traffic.