If you listened to Tech Rag Tear Out Podcast #9 and thought the part about Internet user motivations was interesting.  I got email back from one of the authors – Thomas Stafford – that additional reports have been written by himself/colleagues:

• Stafford, Thomas F. (2003), "Differentiating between Innovators and Laggards in the Uses and Gratifications for Internet Services."  IEEE Transactions on Engineering Management, 50(4), 427- 435.
• Stafford, Thomas F., Marla Royne Stafford, and Lawrence L. Schkade  (2004), "Determining Uses and Gratifications for the Internet," Decision Sciences, 35(2), 259-288.

Like most "academic" computer science publications it is very hard to find "free" reference URLs, so my best recommendation is to go to a major university’s computer science library and do a photocopy of these there.  Sometimes they can be ordered online for $5-10 earch.