I keep tabs on lots of things on TT and elsewhere in the GMing community, and just recently these three have jumped out at me:
Since March of this year, when I first posted about the site, NearbyGamers has grown to include over 1,800 players. If you’re looking for players, I recommend starting here — NBG is slick, useful and free, and well worth checking out.
The Treasure Tables Forums recently crossed a pretty cool milestone, signing up our 500th member. The GMing Q&A board remains the flagship of the forums, where GMs of all skill levels can ask and answer questions about any RPG, conundrum or tricky situation. If you need help with a GMing issue, you can find it here.
Gaming Spaces, the Flickr photo group I started at the end of April, now has over 30 members and more than 50 photos of game rooms from around the world. If you like seeing where other GMs game, come check it out.