Lolli - Earn bitcoin when you shop online
LoveSales - Find and save products you love, get alerted when they go on sale.
Paribus - Find out for free if online stores owe you a refund!
TrackIf - Alerts you if the price of your favorite products drop
Earny.co - Win prizes on Amazon purchases
Giftwhale - Giftwhale allows you to create personalised wish lists online.