Docufluff - Articles, essays, and game journals on multiple games.
The Harrow - Former roleplaying guide Dru Pagliassotti's archive of articles on roleplaying, gamemastering, and adventure writing.
The Keep - A large collection of files, mostly related to RPGs: systems, rule supplements, information about or for campaign settings, adventures and ideas for adventures, other GM aids, fiction, humour, and miscellaneous RPG material.
Neonflux - Over 100 character sheets for systems in PDF and TIFF format, plus adventures for Dungeons and Dragons and Palladium.
The RPG Character Mortuary - Final resting place for characters who died - tragically or otherwise - in roleplaying games. Accepts submissions.