I think Grinity nailed it here. But I have to laugh at this one:
Sometimes Relatives - particularly 3rd cousins.
Too funny!
I was actually talking to people about this one after a gifted homeschoolers talk I gave last week. Gifted kids tend to gravitate toward the same hobbies and academic interests. Interest based groups give a focus for activity and are self selecting. My son sees other bright/gifted kids at chess club, math competitions, knowledge bowl events, book club, and dungeons and dragons. My daughter has found friends at science club and/or who share her love of horses.
People seem to have less success when they advertise for a gifted playgroup. (And yes, I have known people who did!) I think that many parents are hesitant to use the G word when their kids are untested. For others, it smacks of elitism and they would not feel comfortable telling their neighbor or acquaintances about it.
Here's a link to a related article I wrote a while ago:
http://www.bellaonline.com/articles/art10774.aspgood luck!
