Liz England, AAA game- and level-designer writes about theory and getting into the industry.

Dave Johnston, legendary level-designer who designed de_dust. Writes about multiplayer FPS level design.

Raph Koster, game-designer and writer of A Theory of Fun for Game Design blogs about creativity and game design.

Jon Jones, game-artist who has some great universal insights into making a killer portfolio.

Theory, articles and portfolios. A must for every level-designer / environment-artist

Looking for inspiration? Work? Feedback? Help? Go here.

Theory-heavy site about anything level-design.

A friendly Source SDK mapping community. The tutorials found here taught me Hammer.

All-encompassing article describing how to make a multiplayer level from scratch to the end for a realistic setting.

Level-design tips from the 'Sages' of level design. (Including: Levelord, Romero, Bleszinski)

Always insightful videos about a wide array of subjects important in the games-industry.

Daz walks through custom Quake and Source maps and expertly analyses them.

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Like LevelHead, explains examplary examples of good game design.

James Partridge shares insights from his favourite Half-Life 2 map.