It depends on your niche or products, there are a multitude of routes you can take.
If you're looking at "peddling" other hosting, information, or products, Commission Junction can be a decent affiliate. CJ often shells out decent commissions on their hosting programs.
If you're interested in pay per click contextual advertising, I'd recommend Infolinks.
Amazon's affiliate program isn't a bad way to go if you're up for selling products. Just be careful not to configure anything too spammy if you're running Adsense on the site.