Labyrinth Lord (Moldway's retroclone)
Pbphouse (a place to play rpg by forum)
The White Marches (a rpg by email)
Odd74 (a forum on od&d)
Philotomy (advices on od&d, very useful)
Grognardia (a blog on old-school rpg and more)
Goblinoid games forum (a forum for Labyrinth Lord and other products)
Brave Halfling Publishing (the famous rpg publishing house)
Sham's Grog'n'Blog (a blog on Od&d)