Creddon - Tweet for a cause and a sponsor will donate $1 to charity
UpEffect - Crowdfunding for social good products
Raffle of the Day - Win your favorite products. Give to your favorite charities.
Nifflr - Use computer's processing power to earn money for charity
eSolidar - Charity shops and online auctions to support great causes
Public Design Vault - 500+ design tools for public good, all in one place