I’ve talked a few times about evreward.com. Before buying anything online, I go there and check where to get the most money (or miles) back. Why not earn something as you part with your hard-earned cash? The only other website I tend to use to find these portals is Cashback Holics. Between those 2, I figure out the best shopping portal to use and it takes me a grand total of about 30 seconds. For those who use these religiously, you understand how it can add up to hundreds (or thousands) of dollars a year in cash back.
As far as which shopping portal is best, you’ll just go where evreward sends you. Eventually, you’ll sign up for all of the portals and pretty much rotate through them. I use Mr. Rebates, Big Crumbs, and FatWallet the most. The best of the newer crop have been ExtraBux and TopCashBack. It’s free money, so I never mind spending a few seconds to get the most cash back.