Affiliate Program Suggestions?
 

We are getting ready to launch some new sites in our affiliate program and we wanted to start using cascading billing. Instead of writing our own system, we were looking at some options out there.
I would love to get people's opinions on NATS & MPA3?
Any suggestions? What's the most important part of a program for you?

(Thanks in advance!)

important: no shaving, tracking nocookie visitors, an option to receive an email after every signup, an easy interface (I hate having to click 5 times, chose a campaign, click 2 more times to get a link code),...

Use NATS! :thumbsup I'm using it as backend for my program and it rocks.

Also, is there any other backends that anyone else is using that they like?