Mix Tapeology
Pure Content's Sean O'Brien mentions a June 2002 Mojo magazine article about some research done on the nature and effect of mix tapes.

Two researchers from Hamburg University's Ethnological Institute studied almost 150 mix tapes compiled by about 100 people, including an 80-year-old man. The study found that compilation tapes can be used to communicate potentially tricky emotions; that mix tape makers have an affinity for "concept" collections, in which all the songs -- though stylistically different -- share a common musical theme; and that men find the mixed tape a potent way to share emotions. Nick Hornby, come on down!

After a quick search, I can't find any Web remnants of this study. Does anyone have a lead on the text of the actual research report? Might make interesting reading.