These are albums with only interview material, put out by some small-time companies who for some reason had rights to use these interview recordings.
- Limited Edition Interview Picture Disc
- The Interviews, Volume 2
- The Classic Interviews
- Frank Zappa - The Interview Sessions
A list of interviews: http://home.online.no/~corneliu/interviews.htm
Check out the Interview with Jane Pauly, June 7, 1989 on the Today Show. Short and ascerbic.