I tried the SFI Affiliate Center website, but had a bad experience. It looked like it had the potential to be a good program, but upon registering, I had a long questionnaire to fill out. I did an accidental keystroke that put me on another page, and when I tried to back up, I either couldn't or all the info. was gone. The thing is, htere are so many oppurtunities out there, if I'm on a site that's hard to use or doesn't work right, I move on. Especially if I lost a lot of time because of it. There's no good reason for sloppy design.
I also tried GDI, which looked very promising, but I had problems with that one, too. First, they asked that I use my paypal account for a $10 fee, after a week trial period. All-right, I'll try it and see what happens. But when I got to the page where I sign up for a website, they asked for my password to paypal on their webpage. I didn't like that, on top of the fact that if it's free for a week, they shouldn't ask for anything, even proof of ability to pay, up front. So I passed. There's enough stuff out there that I shouldn't need to put up with any shenanigans.