PND: Philanthropy News Digest (The Foundation Center)
A weekly online newsletter about private foundations. Includes updates about grantmaking, funding programs, gifts and bequests, policy changes, personnel, etc. 
http://www.fdncenter.org/pnd

RFP Bulletin (The Foundation Center)
A weekly digest of recently announced Requests for Proposals (RFPs) from private, corporate, and some government funding sources. By direct link http://fdncenter.org/pnd/rfp or by subscription at:
http://fdncenter.org/newsletters/index.jhtml

GuideStar
A nonprofit database good for locating information about private foundations and other nonprofit organizations. Search capabilities are relatively unsophisticated. A benefit is the direct links to PF990's (income tax returns, showing the year's giving history of the foundation), which were once cumbersome to locate.
www.guidestar.org