Listed in an arbitrary order, including EGF and IGF sites.
English-language Go sites, with British connections , are listed separately. This page does not include Go servers  or Suppliers of Go books and equipment .
An extensive library of professional game records, player biographies, Go history and current events, and articles about Go technique.
This is a Wiki Wiki Web  site, meaning that anyone can edit and add new sections to it. Lots of excellent information has already been added.
Collection of links to Go videos (interviews, pro lessons, tournaments, etc).
Provides an index to many Go videos on YouTube .
Also has an email and online news service 
Collection of instructional Go videos by Chinese Go teacher.
Find locations of Go players near you.
Pro news and teaching (from Australia).
Collections of problems, game records with search, teaching material and so on.
Collection of short videos about Go from Peter Brouwer 6D and Kim Ouweleen 4D in Amsterdam. Pro movies are by Kim Sung-Rae 8p.
Go blogs and various resources and links.
News blogs from the various online Go servers and other events.
Professional tournament results and game records.
A web interface to Thomas Wolf's GoTools. It solves simple problems in seconds.
An American Go website for children
Online Book 
By Milton Bradley.
Online joseki dictionary.
A collection of Go problems with time trials at different levels.
Huge collection of Go game records, daily updates, pro commentaries
News blog of pro games, with viewable game records, by Sorin Gherman.
Go news, commented games, stories, pictures, etc.
Alex Dinerchtein's site about sanrensei openings.
Audio and other Go lectures by Guo Juan, 5p.
Some of the Go photos uploaded to photo site Flickr.
Other rule sets, boards and pieces and so on are listed here.
Entry for Go at Trad Games site. Site describes lots of games.
Held on European Go Database .
The Japanese Go Association. The link above goes to the english part of their site, where you can follow the professional Go tournament scene.
Correspondance Go society with forum.
Large database of games, but no way to download them. Try gobase.org first.
Ritchie Press  spoof book publisher.