Other than Adsense, eBay and Amazon, what are the best ways to earn money through Hub Pages?
You can sign up for various affiliate programs, and refer people to their offers. There are many websites where you can look up various offers and choose which one suits you best. Just Google it!
Currently I'm trying my luck with Text Link Ads, they pay you $25 for each new referral. You can check the hub it might give you a better idea what I'm talking about.