A friend has made a track using tape-loops (like throbbing gristle) and also has written an essay about manipulating tapes and a tape-deck to make your own loops (sorry, just in German!):
The track:
http://www.hexachord.org/Music/in_all_meinen_gliedern.mp3
The essay:
http://www.hexachord.org/Ressources/cass_loops.htm