Here is a list of Affiliate Software solutions that work with PayPal:

AffiliateShop

GroundBreak Ultimate Affiliate

LeadHound

MyAffiliateProgram.com

Advanced Marketing System AffiliateGuerrilla AffiliateNet Affiliate Tracking Network Affilliate Software ProTrack AffiliateWiz Aff Manager AllAffiliatePro AShop Affiliate Sales bbvt_aff ClixGalore DirectTrack FastClick FreeFiliate.com Modulocom Affiliation Server MoneyCart MyReferer YOURcom