Efurb, a site for refurbished electronics, offers a $10 Credit just for signing up and it appears once you go to check out.
Earn Unlimited efurb Credits
That's right. No limits. Share efurb with as many people as possible. They automatically get $10 towards their first purchase when they sign up through your link. You earn $10 per invite as soon as they make their first purchase. It's as simple as that. The more you share, the more you earn!

http://www.efurb.com/invite/EFC19546