Adsense now offers text links for their product referral program:
http://www.problogger.net/archives/2006/04/21/adsense-announce-text-links-for-referrals/
http://www.mneylon.com/blog/archives/2006/04/21/adsense-text-referrals/
http://adsense.blogspot.com/2006/04/announcing-text-links-for-referrals.html
http://www.problogger.net/archives/2006/04/21/adsense-announce-text-links-for-referrals/
http://www.mneylon.com/blog/archives/2006/04/21/adsense-text-referrals/
http://adsense.blogspot.com/2006/04/announcing-text-links-for-referrals.html