Hoongle

"Hoongle.org is an Internet search engine that adds a social purpose to searching. For every search you do, we donate 20 grains to rice through the UN World Food Program to help end hunger. Our mission is to make the world a better place one search at a time."

Hoongle is basically a custom Google based search engine, in which Hoongle donates the ad profits that google gives them directly to the UN World Food Program. Hoongle also has all the standard Images/Google Mail/and more links on top for easy access and familiar interface.

I've made Hoongle my default search engine, which is easy to do with their search plugin, which I'd like to point out is not a toolbar plugin, it just adds itself to your existing browser-based search engine list. It works at the very least in Firefox, Chrome, and Internet Explorer.

Hoongle donates 20 grains of rice per each search a user does.
Someone asked me today, "20 grains of rice, that doesn't seem like much,"
and I replied: "well, 20 grains x 1000 users x 50 searches = 1000000 grains of rice," so it does indeed quickly add up.