Here are links to some great resources for nonprofits and foundations:
Nonprofits
Foundation Center
Idealist
National Council of Nonprofit Organizations
Philanthropy
Center for Effective Philanthropy
Council on Foundations
Grantmakers for Effective Organizations
Monitor Institute
Finance
Charity Navigator
Guidestar
Nonprofit Finance Fund
Communications and Social Media
Beth Kanter
NTEN
Publications
Chronicle of Philanthropy
Nonprofit Times
Stanford Social Innovation Review