Picaboo is offering a $10 credit for each friend you refer! You can earn up to $200. That's a lot of photo books!
Here is what you do:
Sign up with Picaboo and Install Picaboo X.
Scroll down to bottom of page and click on New Referrals
Get your referral link and share it with your friends!
They don't need to make a purchase, just sign up and install. Here is a link to Referral FAQ.