Chess.com
Online chess community where you can play chess, learn strategies and tactics, read chess news, see book reviews, find rules & tips
Association of Chess Professionals
The Association of Chess Professionals (ACP) is a not-for-profit organisation, the closest thing in existence to a trade union for professional chess players.
ChessBase
Publisher of high quality chess programs and databases. Offers a free access to a regulary updated online database
ChessGames
searchable chess game database and community
Chess Central
Great collection of downloads, dvds, equipment, books
London Chess Center
London Chess Center is a good resource for news views and books on chess with access to online books