RPG-specific Websites

Alternity

AlternityRPG - Official alternity system resource.

Call of Cthulhu

Yog-Sothoth - for all aspects of Cthulhu and Delta Green.

Champions

Champions Write-ups - your favorite heroes, Champions style.

Cyberpunk 2020

Blackhammer Project - Cyberpunk 2020 site.

Dungeons & Dragons

D&D Adventures

AD&D 1st edition

Dragonsfoot - specializing in 1st Ed. AD&D.

Glorantha

Lokarnos - Index to Gloranthan websites.

Hackmaster

Mikeeze Wurld - Hackmaster specialist.

Traveller

BITS - British Isles Traveller Support.
Downport - for all versions of Traveller.

Warhammer Fantasy Role-Play

Mad Alfred's WFRP Pages

Other

Aether Traveller - concentrates on the old GDW games.