Starring: (distinctly unfinished)
Cambridge Below, a LARP system and setting.
London Below, a campaign and a campaign setting for D&D (3 or 3.5ed).
Character Backgrounds: (listed in order of 'being worth reading in their own right', from best to worst)
Marras of the Morning Tower, 30th-level Monk
Riverbird, GURPS 100-pt winged girl
Thelamir of the Forest