These are all places that I visit pretty often, for one reason or another.
The Forge Forums are where I talk about game design with my game design buds. Excellent, excellent place. I can't ever thank Ron and Clinton enough for starting up this site. Be sure to poke your head in on the Alyria forum; Seth ben-Ezra's game is really worth taking a look at. Or several looks.
Harlekin-Maus is Zak Arntson's game design page. He's pretty cool. Take a look at Shadows; Torchbearer owes a lot to ideas that Shadows made me aware of.
Memento Mori is where Jared Sorensen hangs his hat. Another good guy. Take a look at Idoru, a Calligrapher's Sword game waiting to happen.
lumpley's site is where Vincent Baker, a.k.a. lumpley (no caps, please) has a pile of Good Stuff. Like, really good stuff. Go and poke around. It's cool. And, seriously, can you think of a domain name cooler than septemberquestion? Dude.
100 Flowers is my buddy Jonathan Walton's page. Recently, he added some content to it. Good job, dude! Take a look.
There are a thousand places I could link you to, thousands upon thousands, but, seriously, no. Half the enjoyment is in the journey, after all. Enjoy it, and may you dream of better places.