Textfiles.com now has exactly 300 role-playing games articles, dating from the 1980s and 1990s. Textfiles.com, which recently celebrated its tenth birthday, is a repository of various material from bulletin-board systems or BBSs, the modem-based dial-in systems that existed before the World Wide Web.
Most or all of these articles predate Dungeons & Dragons third edition. Still, a lot of it is useful for inspiration, or just interesting for historical purposes. Leave a comment and let me know if you find anything particularly good.