Warning: this is a bit of a self-serving post, but it does benefit you without too much effort (but some!). Read on ...
HERE is my referral link to sign up for one of the most popular and reputable cash-back portals called Ebates.
If you sign-up by 12/31 and spend at least $25+ at just about any online retailer (of course, only do this if you're going to anyway!), you'll get a $10 gift card from Walmart (or a $10 Ebates credit). Full disclosure - I get a bonus for you signing up. But, seriously, only do this if you really want to and have something to buy for $25+ online.
If you aren't familiar with shopping (or cash-back) portals, you can read more about them HERE from a previous post on my blog. I really need to update that post, but there's some good info in there (and, yes, some more referral links).
As I mention in that post, you should always check www.cashbackmonitor.com or www.cashbackholic.com to see what the best shopping portal is (highest percentage cash-back or reward points - for an airline or bank shopping portal) to use for whatever given online retailer you are using. But you might want to limit how many different portals you use, or at least make sure you read the details on the portal's rules for paying out - as some require that you build up your balance to a certain level before they'll pay out (and it would stink to never build your balance up to that level - so that you never benefit from it!).