These sources will help you find RFPs (also called RFAs) and grants.
Fundraising & Grants Directory for nonprofit organizations and schools
You can search grant funding resources by state and the Grantsmanship Center also offers training for groups/people to be able to compete for available grant opportunities.
This resource allows you to check out nonprofit organizations, charity organizations, and look at the reports on them for free. You can write a review on any experiences you've had with a charity organization as well. You can also access the Federal Register for new grant announcements and information. Just go to Resources at the top and choose Federal Register.
The Chronicle provides news and information for tax-exempt organizations. In addition, it offers lists of grants, fundraising ideas and techniques, statistics, reports on tax and court rulings, summaries of books, and a calendar of events.