While this isn't a Web site, this listserv may be of interest to researchers. Designed with new librarians in mind, this new and unmoderated list is a forum for idea exchange and discussion of issues, trends and changes in the profession. Experienced information professionals are encouraged to participate. Volunteers use Find to seek out just the right place to get involved, searching by zip code, how far they want to travel and by category, for example.
Nonprofits can post openings directly to the site, and volunteers can even sign up online.
You can also search this site's non-profit directory. Just enter your search term, like the name of an African-American, and let the engine do the hard work for you. American fraternities and sororities. There are many other other categories to explore. Some of the categories load slowly, so be patient.