I also support competitions for gifted kids. Competitions help kids advance their abilities, plus they provide an opportunity for socializing with other children who share similar interests. The book Competitions: Maximizing Your Abilities by Frances A. Karnes and Tracy Riley, is an excellent source of more than 275 such competitions.
Programs for Gifted Homeschooled Teen
Gifted and Talented Expert Advice from Noreen H. Joslyn, LISW, ACSW