Ok, here are my own main picks so far:

-the World Wildlife Fund (WWF). Nokia sponsors this as well, so it's a good fit in more than one way.

-www.kiva.org . They facilitate micro loans to third-world entrepreneurs. Mostly people trying to make a living off their unique natural resources.

-http://www.fairtrade.org.uk/about_us.htm . Lately I'm becoming a huge advocate of fair trade.