Guidestar Mission: To gather and disseminate information about every IRS-registered nonprofit organization including each nonprofit's mission, legitimacy, impact, reputation, finances, programs, transparency, governance, and more.
The Foundation Center (in NYC): The leading source of information about philanthropy worldwide. Foundation Center maintains the most comprehensive database on U.S. and, increasingly, global grantmakers and their grants (Foundation Directory Online is available onsite at any Rutgers Library.)
More links on NonProfits