Affiliate sites are often categorized by merchants (Advertisers) and Affiliate networks. The main categories are:
Search affiliates that utilize Pay per click search engines to promote the advertisers offers (Search arbitrage)
Comparison shopping sites and directories
Loyalty sites, typically characterized by providing a reward system for purchases via points back, cash back or charitable donations
Coupon and rebate sites that focus on Sales promotions
Content and niche sites, including product review sites
Personal websites (these type of sites were the reason for the birth of affiliate marketing, but are today almost reduced to complete irrelevance compared to the other types of affiliate sites)
Blogs and RSS Feeds
Email list affiliates (Owners of large opt-in email list)