The reason affiliate marketing sometimes backfires is that you can't filter out who's writing about your product and what they're writing. 37Signals stopped taking new affiliates, and instead started a 'Tell-a-friend' program coz these kinds of recommendations are more personal and have better chances of getting looked at favourably. If I could choose, I'd pick a referral program over an affiliate program. But thanks for listing your product. It's interesting to know who's behind affiliate marketing today.