right now on StumbleUpon, you can earn a $10 gift card to Amazon for every 5 friends you get to sign up for StumbleUpon (which is completely FREE).
Just sign up here and then you will get an email with links to refer your friends through Facebook, email, link, Twitter.
Feel free to share your links in the comments!
You can watch the video below which shows you what StumbleUpon is:
Read all the details of this promotion here.