This wonderful site currently has just over 100 documentaries on American roots cultures. It's a site loaded with classics including films by Les Blank, Tom Davenport, and Alan Lomax. It's indexed by film, filmmaker, region, subject, and featured individual. If you're interested in Dewey Balfa, for instance, you can quickly discover he's included in Les Blues de Balfa, Cajun Country, Cajun Visits: Visites Cajun, and Homemade American Music.
It's a site especially rich in blues and Appalachian music though there's much more. In addition to the films/videos, there are essays about the folk traditions and making of the films. There are also study and teaching guides, suggested readings, and links to related websites.
The creation of the site was spearheaded by Tom and Mimi Davenport in a coordinated effort with filmmakers, folklorists, web developers, and The University of North Carolina to preserve these works and provide greater exposure to them.