Websites that help you make loans or investments in small businesses

Kiva.org:  matches entrepreneurs in poor countries with lenders in rich ones. You can choose whichever project/business you want to fund.  For instance, this grocery owner in Kabul needs only $50 to complete a $1,075 loan to buy inventory for a year or this furniture maker who needs $350 to complete his loan. Little actions can build up quickly through sites like Kiva.

MicroPlace (another microloan site)

AGoodCause (which lets you raise money for charity while you shop)

For those who want to spread the message about their own cause through their social networks, Change.org and Causecast are great places to start.