You can apply for Marketiva Affiliate program by filling out an online form on their website. Marketiva allows customers to trade as few as $1, and it's not opened to US residents. However it does convert, with about 10 users I referred, I got about $1000 in 3 months because one of them really traded lots of money. So I would say there's a conversion of 10%, meaning one in 10 users will bring you affiliate commission.

Your application is reviewed after sending it, and additionally they might ask you for a copy of your id and eventually your last bill to prove you are really living where you said you are (and to prevent money laundring).

The Marketiva Forex affiliate program offers only a commission sharing option (actually revenue sharing), where you get 1 point for each position that your referred user closed (to be taken into account the position vary with at least 4 pips in gain or loss). As an example, if someone trades pairs up to $100000 and closes those with a difference of at least 4 pips, you get $10. So if you refer someone that closes 10 positions like this daily, you would get up to $100.

Marketiva also lets you set up a private communication channel if you refer at least 100 customers, so you can discuss Forex trading tips and strategies with them.

Once the money start piling up from the Marketiva affiliate program, you can withdraw them by wire transfer, WebMoney, Liberty Reserve or E-Dinar. Even if they don't offer Paypal as a payment option, I was able to get them in paypal by using WebMoney. Sign-up here: Marketiva affiliate program

Name: Marketiva affiliate program
Commission: you get 1 point for each position that your referred user closes (translates to about 10% commission)
Conversion rate: up to 10%
Pays through: Wire-transfer, WebMoney, Liberty Reserve or E-Dinar
Resources: Gif and flash banners, coupons for emailing.
Sign-up at: Marketiva affiliate program