The Chronicle is an excellent source of news on the foundation and nonprofit world, and there is a grants database. You do have to subscribe, however, to access the database. There are a limited number of articles available for free.
Don't forget that you should call the foundation or agency you are interested in to request a copy of its annual report and grant guidelines. These are often online and can be downloaded.
NOZA is one of the best free sites for grant funding information.
You can purchase a subscription for more complete information, but a free account allows a search by foundation name, location, keyword, etc. NOZA then generates a list of charitable contributions based on your search criteria.
Fundsnet is also a free resource and might be worth a try in the beginning of your research. The information, however, is limited and you'll need to go to more comprehensive resources in the end.
Seeking Grant Money Today is a helpful source for information about the grant requesting process. It also lists grant opportunities as they become available. Not a comprehensive source for information on foundations, but it is useful. You might want to subscribe to its RSS feed to receive announcements that might be helpful.