TF Portal.Net is a joint English and German website cover all the Team Fortress games.

TF2 Forum is the center for discussion, game strategy, and resources for Team Fortress 2. You can chat with the community, or take a look at their information sections.

TF2 Tactics contains downloads, exploits, tutorials, skill videos, tips & tricks and training information for TF2.

TotalHL.hu is a Hungarian Half-Life portal.

Tweak Guides provides incredibly useful information and tips on how to get the most out of your hardware and games.

It might seem strange to add Wikipedia to this directory but it contain some very useful information for Valve’s fans. The sections on the games are very detailed. It is also available in many langauges.

World Of Level Design is a website/blog aimed at those interested in Environment Art and Game Level Design. It contains plenty of original content, including tutorials, articles and interviews. There is also a lively forum.

World Of Moo is a blog with a small group of writers. They blog about many aspects of gaming.