I just saw that the Amazon Flexible Payments Service (Amazon FPS) service is out of beta and has a nice offer: no fees on transactions for 90 days for transactions up to $500,000.
That seems nice!
I'd also personally love to see more competition in this space. I don't really know how these systems work - would this be another payment gateway for Ubercart? Is it even possible or reasonable for someone to try to build this?


