(MONEY Magazine) – Want a painless way to give more? Shop through a Web portal that funnels a small portion of what you spend at major e-commerce sites to a charity of your choice. At least half a dozen sites do so, but the amounts that go to charity and your choices in beneficiaries vary widely. Ebates (www.ebates.com) and iGive.com (www.igive.com), each with hundreds of stores, thousands of charities and many bonus offers, have the edge in breadth. The trade-off is skimpy rebates. At these three sites, your shopping can do more good:

CharityMall (www.charitymall.com). This site offers perhaps the best mix of generous rebates and notable stores. You can chose from among 203 charities or designate another without much hassle. The 100 or so online stores include J.Crew (5% of what you spend goes to charity), Lands' End (5%), Delias (4%), CDNow (6%), Gap.com (5%), the Disney Store (5%), Sony Music Direct (10%) and Harry and David (6%).

CharityAmerica.com (www.charityamerica.com). You'll find 130 stores, some 900 charities and rebates that are among the highest available. Best bets: The Sharper Image (10% to 15%), Hickory Farms (7%) and 1-800-FLOWERS (6% to 8%).

4charity (www.4charity.com) With just over 60 stores and 150 charities, the selection is small. But if your favorite site does show up, your donation can be significant. The roster includes Amazon.com (5% to 30%), Swiss Army (12%), Brooks Brothers (8%) and Esprit (7%).

--LAURA PERRY