When I was at Valpo I did a project on researching all of the groups that had been on campus. My best resource? Yearbooks!
Go to your library, and find the yearbooks. Usually there's an archive or a set in the reference collection under local history. A librarian can help you find them if they're off in some local history archive.
Usually you can flip through to find the photos of organizations, and greek orgs are often in a clump. Sometimes it's just alphabetically by org, but often the photos will be sports teams, greek orgs, service orgs, business/academic orgs, general clubs, etc.
This is also a great way to find out what locals may have been on your campus. In our case, there were some men's locals that became fraternities in the 1950s and 1960s, but our sororities were local until 1997-2000. You can find out a lot of interesting history that way.
Also, it can give you clues as to why orgs left-- sometimes you can see the number of members in the photo get smaller and smaller, and then the next year there's no photo.
