Points2Shop and Cashle offer cash back for nearly 2000 merchants and products. To find cash-back offers, visit the main offers page and select the "Cash-back offers" check-box.
A cash-back offer involves you making a purchase from an online store, and later getting a certain percentage of your purchase back (the percentage varies per offer). If you were to spend $100 at a site that offered 5% cash back, you'd get back $5.
Things to note. Be sure to clear your cookies before doing a cash-back offer, just to make sure you're purchasing through the right affiliate link. If you do complete a cashback offer, it is best to wait a few days, then send in a ticket requesting that they credit your cash-back because the traffic on these are low, and they don't check often.
If you're planning to make a purchase from any of the supported sites, be sure to use the cash-back offer from here instead, it's a great way to save some money and boost your earnings on p2s/cashle!
The majority of the cash-back deals are not at places where you would shop often, but you may just find exactly what you're looking for!