Other in-character or story-based sites:
Cheldzan Jokku: the home on the web of M.C.A. Hogarth's Jokka.
Flight of the Godkin Griffin: a tale in journal form, with audience participation! (also M.C.A. Hogarth) Link is to website, journal is here
Sythyry: another tale in journal form, set in the World Tree universe, with audience participation of a different sort. Link is to website, journal is here
The Book of the Gear: yet another fictional journal, a travelogue of sorts to Ursula Vernon's Gearworld
The Dionaea House: a creepy tale of suspense, written as emails.
Anna S. Oppenhagen-Petrescu: the credentials of a vampire researcher (a creation of Catherynne M. Valente)
Webcomics:
Digger (pay site - current strip is free, but archives are not)
Authors:
Stardancer.org: M.C.A. Hogarth
Cleolinda Jones (the creator of Movies in 15 Minutes)
Pegasus Nest: Yoon Ha Lee
Michelle West (site updates rarely - her blog is more active)
Neil Gaiman (also check out his very active blog)
