'Cassette Culture was an offshoot of the Mail Art movement of the 1970s and 1980s. It was a postal-based music distribution scheme where the artist would sell or trade music on compact audio cassettes via a loose network of other artists and/or traders... In the UK Cassette Culture was championed by marginal musicians and performers ... as well as small tape labels [Con Tapes, Datenverarbeitung, Snatch Tapes, Sterile Records, Pleasantly Surprised, Third Mind Records, Cause For Concern, Onslaught magazine] ... Cassette culture received something of a mainstream boost when acknowledged for a short while by the early 1980s UK rock media. Both the New Musical Express (NME) and Sounds, the main weekly music papers at the time, launched their own Cassette Culture columns...'
From Cassette Culture, Wikipedia
For some images of cassette packaging, including CA's Sinclair's Luck, see Rarecords
CA at Discogs: http://www.discogs.com/artist/Cultural+Amnesia
Vive le cassette at the Snatch site
Homemade Alien Music -- A series of podcasts of cassette music of the 80s and 90s from the archive of US cassettist Hal McGee
The Cassette Mythos Guide
Cassette Culture discussion list/site