The Citadel is an archive of information for George R.R. Martin's A Song of Ice and Fire.
New to the series? Read our spoiler-free review of A Game of Thrones.
[Note: There's a couple of small errors in this report, but on the whole it's a thorough recounting of Martin's reading from his original Westerlands material for The World of Ice and Fire.]
The Westeros network consists of several different sites, including a forum and a wiki, for all your A Song of Ice and Fire needs.