First, gamedev sites and forums:
gamedev.net
devmaster.net
idga.org (warning: their site is REALLY slow, the forum may take 20 minutes to load... don't give up as it takes a long time).
Then, indie communities:
tigsource.com
www.indiedb.com
www.moddb.com (well, sorta the same as indiedb, the forums are actually shared)
Important blogs to send your PR stuff:
rockpapershotgun.com
indiegames.com
pcgamer.com
Shareware distribution sites:
tucows.com
softpedia.com
download.com (to upload to them, it is upload.com)
Advertising services:
google ads
game-advertising-online.com
PR services:
gamerelease.net
gamespress.com
I will add more stuff as I remember (most of those are post-its glued to my monitor)