Groundspring
http://www.groundspring.org/
Groundspring.org is a nonprofit organization that aims to improve the effectiveness of the nonprofit sector by providing simple, affordable, and integrated services for small to medium-sized nonprofit organizations to help them become effective users of internet technology in their fundraising and management of donors and supporters. Groundspring.org is a member of the Tides family of organizations

GuideStar
http://www.guidestar.org
The Guidestar website contains extensive operational and financial information about more than 850,000 nonprofit organizations, providing prospective donors with the ability to compare charities, monitor their performances, and give with greater confidence.

Network for Good
http://www.networkforgood.org/
Network for Good is a nonprofit organization dedicated to using the Web to help people get more involved in their communities - from volunteering and donating money, to speaking out on issues. Its website, which is powered by GuideStar and VolunteerMatch, has information on giving and volunteer opportunities for more than 850,000 nonprofits nationwide.