Anyway one of these sites that use the PTC system is AdverCASH (yes you might notice it is has a refer link attached to it... but since I am refering you, maybe you can be so kind to join under me ^_^?).
So advercash works really simple. For each advertisment (now I will call it ad for future reference) you click, you get 1 cent. For each member you refer you get 1 cent. For each link YOUR REFERRAL clicks you get 1 cent. The min payout is 10 usd. They currently payout only to PAYPAL.
Join Advercash by clicking on the following link: http://www.advercash.net/signup.php?ref=inaga
Currently my stats are as shown:
I will post more sites later :)!