Non-profit organizations come in all sizes from small neighborhood associations to large hospitals and universities. If you are researching an arts organization, community theater, hospital, union or educational institution, look for their non-profit status.
US Nonprofits
Despite their tax-exempt status, nonprofits are required to file with the IRS. They must file a 990 form. 990's contain financials, lists/descriptions of grants, activities, mission statements as well as lists of officers & directors. Below are sites to find the 990 forms, a digest of them or external analysis about the organization based on the organization's filings.
International NGOs