There's a new app for iOS and Android called ibotta that can potentially save you lots of money. I'd say it's most like SavingStar, in that you select offers before you go shopping, and get the savings after you make your purchase.
However, with ibotta, you don't need a store loyalty card. Instead, you upload a photo of your receipt through the app, then scan the barcode of the qualifying item, also through the app. I've redeemed one offer and found the app very easy to use with my iPhone 4S. Their offers are for many things you probably buy anyway - the offer I redeemed was for Glad food storage containers. Current offers include Kellogg's cereals, Huggies diapers and wipes, Chapstick, Dove and many more. (Update 1/10/2013: I've since redeemed approximately one dozen offers and continue to love ibotta!)
Maybe the best part about ibotta is that it works at so many stores, including Target, Walmart, Walgreens, CVS, Rite Aid, Kroger stores and their affiliates, and Safeway stores and their affiliates. See the full list here. You can cash out your savings through Paypal when you hit the $5 minimum threshold, or donate your savings to a school or the United Way.
Right now, ibotta is offering a $5 sign up credit when you join here and redeem at least one offer. (I'll get a $1 referral credit, so thank you!) The $5 offer