Care2 Click To Donate / Freerice

I've been doing this every day since late 2008. Basically, you click the buttons and donations are made to various causes including childcare, animal welfare and stopping violence against women. It's all free and you don't even have to register to do it.

http://www.care2.com/click-to-donate/

Another great site like that is Freerice. You answer questions on different topics and every right answer you make 10 grains of rice are donated to help end hunger :)

http://www.freerice.com/