I've been doing quite a bit of reading about virtual worlds over the last few months. The focus has mainly been on SL and WoW, but some general/theoretical stuff crept into the mix. For now, it's just a list of names; I will come back and annotate them later.
Here's the list, in the order that I read them (or will read them, for those yet unread).
Tom Boellstorff, Coming of age in Second Life
Edward Castronova, Synthetic worlds: The business and culture of online games
-- , Exodus to the virtual world: How online fun is changing reality
Janet H. Murray, Hamlet on the holodeck: The future of narrative in cyberspace
Zach Waggoner, My avatar, my self: Identity in video roleplaying games
Bonnie Nardi, My life as a night elf priest: An anthropological account of World of Warcraft
Ken Hillis, Online a lot of the time: Ritual, fetish, sign
T.L. Taylor, Play between worlds: Exploring online game culture
Celia Pearce and Artemesia, Communities of play: Emergent cultures in multiplayer games and virtual worlds
William Sims Bainbridge, The Warcraft civilization: Social science in a virtual world