It's partnered with CitiBank, so I feel secure with this one:
http://www.obopay.com
You get $5 to sign up, there are minimal fees, and if you're into referrals, you get $5 per referral.
Only thing is, you have to have a cell phone to sign up - and make sure you type it in right the first time! I typed in the wrong number and had to get them to totally clear my sign-up info so I could start again.