Change.org is a full featured Web2.0 site, built around what people want to change in the world around them. You can create a profile and specify what things you would like to change, and find other people who are interesting in similar things, and discuss with them. You can add NGOs and politicians (!) to these topics. They have a system to allow making donations for the NGOs or the politicians. They take a 4.5% cut from every donation made on the website (which is probably used to sustain the website).