Up to Robert
Illustrated Dungeons & Dragons edition guide
TSR-era Dungeons & Dragons (mainly classic)
Traveller
Marvel Super Heroes
The d20 System (a.k.a. D&D3e)
Drafts of homebrew systems
On unified mechanics
The North Texas RPG Con
John Kim’s Encyclopedia of role-playing gamesand Free RPGs on the web
Board game geek & RPG geek
RPGNow
Gamescience
Talmyer