By the way- back to eBay- you don't need members to sign up for you to earn the buy-it-now and bid commissions- existing members' clicks count here too, so you don't need them to sign up via your link to make money off of them- although the sign-ups are nice (for obvious reasons).
blabla, A "get started on eBay guide" might be the best choice for maximsing sign-ups as you're likely to attract more newbies.
And as Badger said- loans pay pretty good % commission but the prrogrammes are more stringent about who signs up (well, the UK ones are- the US ones seem a little easier).
For Poker though, most sites allow you to apply to be affiliates directly, CJ offering for betting & gaming are rather poor in my opinion...