Stuff for Dungeons & Dragons Basic & Expert Sets published in 1981 and edited by Tom Moldvay, Dave Cook, and Steve Marsh.
Daniel Proctor of Goblinoid Games has created Labyrinth Lord, a clone of B/X D&D.
I wrote lots of stuff about classic D&D on my infogami site. I have an archive of it until I have a chance to clean it up & move it all here.
RC Gnomes: A B/X write up of a Gnome class based on the AD&D conversion notes in the Rules Cyclopedia.