Hi
I use a site called pigsback.com, on this site you can earn piggy points, some of the points are free by just clicking on the partners link, using can also earn points by signing up for newsletters that interest you, also there is another way of earning points is by clicking on a partners link and if you use their site to shop through you earn points, the points vary for each partner some say you can earn 4 points per £1 you spend on their site.
They have just set up a new way to earn points which is by registering your card details and if you use your debit card in certain stores on the high street you can also earn points.
You can also earn points by referring friends, they have daily competitions where you have the chance of winning points.
The best bit about this is that the points are converted into money, which you can then use to get gift vouchers, pass your points onto a charity or even buy pigsback.com items.
I have found this website very useful and informative, they are updating and adding more partners every month.