Surveys.com

This is a great PPS website. They have already paid me twice so this is a trustworthy site.

Although their referral system is individualized (you can only send invites by e-mail), they pay well per survey (I've recieved a couple 5$ surveys).

Although they don't send survey invites as often as other sites, this is a great way of making money with almost no effort.

Check it HERE