I'm in the process of setting up an affiliate program and i'm considering using omnistar affiliate software osiaffiliate.com, it looks great but I can't find much info on them. Jam also looks nice.
I used to work for omnistar etools, the company behind omnistar affiliate. While I never used their affiliate product from a user's perspective, I can tell you that the company is ethical and really stands behind their products. Anytime a customer had a question or needed help with the software, the person in charge of omnistar affiliate customer service (who I happened to eat lunch with quite often) really did a lot to make sure the issue was resolved quickly. I haven't worked for them for a few years, but I wouldn't hesitate to recommend their products to anyone I know.
You have to wonder about any affiliate software company that doesn't use its own software to track their own affiliate program! OSIaffiliate or Omnistar affiliate uses shareasale.com: http://www.osiaffiliate.com/affiliate_program.htm WTF! so they expect you to pay for their software but inhouse they use shareasale LoL