Ametrine,
You might get some good contacts that way, but you might get better response just posting for families with young kids interested in "x" (whatever your kid's big advanced interest subject is). Many parents of gifted kids take a while to figure out why their kid is three times harder to parent than the neighbors', and so wouldn't answer a call for gifted kids, because after all, it isn't that unusual for kids to know all their letters and letter sounds when they are two, and to learn to read by themselves...
