I imagine these is already on your radar, but it seems appropriate at this point to link to two of the 1000 True Fans essays from a few years ago.

Original -- http://www.kk.org/thetechnium/archives/2008/03/1000_true_fan...

Followup -- http://www.kk.org/thetechnium/archives/2008/04/the_case_agai...