I am a big fan of the concept of micro-finance and also of finding ways to get my kids involved in philanthropy. For the five to twelve-year-old set (alas, none of mine qualify) One Hen is worth a visit. It is based on a children's book but the site teaches children about microfinance and gives them a way to participate in it. They play games on the site and earn "beads" which are translated into actual loans in the real world for small-business ventures in the developing world. It's a sweet site and a lot less work than a lemonade stand!