Ask HN: Simple way for service to pay money out to users?

Is there a service out there that makes it easier to send users money? For example, in a marketplace user-a pays $100, user-b gets $70, while the marketplace gets $30? Also the marketplace would need to hold on to the money for one month or so to be ready to handle any chargebacks or requested refunds.

I've looked into a few solutions:

Amazon FPS - doesn't appear to be white label. PayPal (WPP & MassPay) - requires user-b to have a PayPal account to receive payments.

The ideal system would be able to mail checks, direct deposits, and maybe even have the ability to pay through PayPal.