I've got a mental list of people, and if I see that they've posted something I almost always check it out. I don't always agree with them, but their posts are often relevant and/or thought provoking. I'd be interested in hearing everyone else's opinion on this topic.
My list:
dnc101
Dark Knight
BeiKongHui
MonkeySlapToo
Shaolindynasty
rogue
Crimson Phoenix
Fu-Pow
Ground Dragon
The Willow Sword (he always stirs things up)
Badger
sean_stonehart
jon
EDIT: DEFINITELY JWT
Second edit: Sam Wiley...always gets me thinkin'