I use this one http://scour.com/invite/pksanddancer. it's scour, unlike swagbucks, you get a point for everytime you search. you can invite friends and get 25% of their points. you may then trade your points for 25$ visa gift cards.
or try swagbucks. you can earn them and trade them in for amazon git cards, follow this link http://www.swagbucks.com/refer/pksanddancer