Prometheus Society  
   Educational, scientific, and research group for those with extreme intelligence.
   http://www.PrometheusSociety.org/

SesquIQ  
   High IQ society. Membership active in environmentalism and research.
   http://www.angelfire.com/home/sesquiq

The Cerebrals Society  
   A society for those whose IQ falls at or above the 99.7th percentile (top 0.3% of the general population). Members interact via discussion forums and an online journal. IQ tests are available on this site.
   http://www.cerebrals.com

High IQ Society  
   An online community of intelligent persons.
   http://www.smartgroups.com/group/group.cfm?GID=139378

IQuadrivium Society  
   A high IQ society for those at and above the 99.9th percentile.
   http://www.s-2000.com/iquadrivium/

International High IQ Society  
   Five professional free IQ tests to qualify for membership. Members enjoy access to chat rooms, discussion forums, regular online tournaments in chess, backgammon, contract bridge, and Go, as well as difficult puzzles and brainteasers, and the ability to
   http://www.highiqsociety.org/

Intertel  
   An organization of those with IQ scores in the 99th percentile (top 1% of the general population). The goals of the organization are to encourage meaningful intellectual fellowship, foster an exchange of ideas on any and all subjects, and to assist in re
   http://www.intertel-iq.org/

The Intellect-Fellowship  
   A fellowship for intellectuals in the top 10% of society. The fellowship encourages creativity of members, publication of their works and thoughts, engagement in the functioning of the group and participation in one or more areas related to the fellowship
   http://www.intellect-fellowship.org

Pars Society  
   Seeks to provide a peaceful, intellectual and private forum for its members. Proof of intelligence level at or above +2.5 standard deviations is required for membership.
   http://pars.eu.tt

Mega Society  
   Society with an entrance requirement at the one in a million level, it's purpose is to provide members with forums and outlets for their ideas.
   http://www.megasociety.net

Ne Plus Ultra  
   An intellectually oriented club that seeks to gather exceptionally insightful people to discuss ideas across a variety of domains.
   http://www.ne-plus-ultra.net

High IQ for Humanity  
   Seeks to develop the skills of gifted children within their respective countries in the hope that they will stay to develop their homeland instead of migrating abroad. News, child profiles, project information, and sponsor list available.
   http://www.hiqh.org/

HighPotentialsSociety  
   A forum for the intellectually highly gifted. Members must have an IQ of at least 132 (M=100; SD=16).
   http://www.highpotentialssociety.org/

Glia Society  
   Seeks to be a forum for the intelligent and to encourage intelligence-related research.
   http://paulcooijmans.lunarpages.com/