Foundations are required to file a 990 tax form each year. These forms can provide a wealth of useful information about the foundation, including their most recent financial information, officers and trustees, and every grant they gave in that year. The 990 forms are public information and can be accessed in a number of ways:
Foundation Directory Online Free - look up funder by name, tax identification number or location to see a small profile of the funder and a link to their tax forms.
Guidestar.org - both nonprofit and foundation 990s are listed
National Center for Charitable Statistics - both nonprofit and foundation tax forms listed