Thousands, I'm sure. The ones that I follow,
FWIW, are:
- Acaeum
- ENWorld
- Rob Kuntz's Pied Piper forums
- Dragonsfoot (1e/OD&D focused)
- Grognard's Tavern (1e/OD&D focused)
- Necromancer Games
- Canonfire! (Greyhawk stuff)
- Doomsday Games (Greyhawk stuff)
-
WotC Greyhawk forum
I pop in on some others much less frequently: those are my regular virtual geek havens.