http://giftedhomeschoolers.org/Many of them are more of the "nature" not "nurture" camp, as we tend to be, but even so, I have found some good resources from them.
http://forums.welltrainedmind.com/I don't subscribe, but I have had many google searches that have led me here. It's a great group of people overall.
My biggest one after BrillKids is my local homeschooling group(s), both on facebook and on yahoo. That's where you'll find potlucks, field trips, and free zoo days, so don't forget to look there!