ISPE (International Society for Philosophical Enquiry) - Recommended for "high achievement" individuals. Also, I am told that their journal, Telicom, is outstanding. Founded in 1974, the ISPE (originally known as "The Thousand" since the 99.9th percentile is the one-in-a-thousand level) is the 3rd oldest functioning high IQ society. People who join the ISPE enter as "Associate Members" and "qualify for advancement to Member upon demonstrating commitment to the Society's goals via personal achievement and contributions to society". There are several other ranks one can advance to beyond Member. This is very different from Mensa (Mensa means "table" in Latin, suggesting a round table society where all members are of equal standing) and most other societies. ISPE has been known to expel certain members (note Darryl's ISPE and Triple Nine Society entries), although I have only heard one side of that history. With the exception of the ISPE's own unsupervised test, only scores from supervised tests are accepted for purposes of joining the ISPE.
Triple Nine Society - I have only recently (2/09) joined Triple Nine, but am highly impressed with much of the membership, their excellent journal, and the variety of ways in which one can be involved with the organization. Founded in 1979, the Triple Nine Society (or TNS) is the 4th oldest functioning high IQ society. The society is noted to have ongoing political and personal conflicts, and their 2 primary e-mail fora and to some extent their journal, Vidya, reflect this. However, a number of members have started fora which require civil behavior, and in addition to a general discussion forum, there are others that focus on specific topics such as puzzles, religion, business, firearms, health, and others; fora for specific states and other regions; and fora which relate to certain careers (teaching professions, medical professions, legal professions, and others). So you have options in participating in virtually no-holds-barred discussions or those that are more civil. TNS has an annual meeting, and some areas (Colorado for certain, but I believe there are others) have additional meetings. With the exception of a few tests that are only accepted if they were taken before 1995, only scores from supervised tests are accepted for purposes of joining Triple Nine.
One-in-a-Thousand Society - Recommended for those who enjoy civil discussions. Founded in 1992 by Dr. Ronald K. Hoeflin, OATHS started out as a print journal (OATH) only. But as with TOPS, a Yahoo Group now exists, with a fairly active e-mail discussion list. Membership is now entirely free. The journal Termite is now entirely online (effectively the successor to OATH), and there are no admission fees or any other fees. The Yahoo Group shows that there are 82 active OATHS group members, but not all group members actually receive the e-mails. Yahoo Groups allow you to modify your subscription status without canceling your membership, which is very nice.
Glia Society - Recommended for its unique journal and e-mail discussion lists. Founded in 1997 by Netherlander Paul Cooijmans. Paul and I were the first 2 Glia Society members. The society's journal, Thoth, is available in online form free of charge. Material sent to be published in Thoth is not edited. Glia has 2 active e-mail discussion lists (one moderated, one not), which are maintained on Yahoo Groups. The format of posts to the moderated group are fairly restricted with the intention of maintaining a high quality discussion, although this to some extent may stifle spontaneity and creativity. With no fees to join or maintain membership, free e-mail discussion lists, and free online journal, Glia is one of the better groups as far as expenses go. Glia's membership is very diverse, with members all over the world. Thoth and the e-mail discussion lists reflect this very much. Yahoo Groups allow you to modify your subscription status without canceling your membership, which is very nice. NOTE: Most other groups allow non-members to subscribe to their society's newsletter or journal for a fee, or at least obtain sample issues. This is not the case with Thoth, which is very explicitly for members only. Currently NO standard tests are accepted by Glia, only ones designed by Paul Cooijmans and a few other individuals. If you are interested in joining and do not have a qualifying score, I recommend the Cooijmans Intelligence Test, which does not have a strong culture bias and contains many lateral thinking association problems. The CIT can be found through this link.
Ludomind Society - "The goal of the society is - without any exception - to present BEAUTIFUL puzzles."
Milenija - Society focused on the development of high-range abstract spatial tests.
Genius Society - "As we need a measure of creativity, in addition to a High IQ, membership will be open only to individuals who are engaged in scientific research as demonstrated by peer-reviewed publications. The Genius Society aims to foster communication, friendship and cultural exchange among its members."
ISI-Society - 99.93 percentile society. "ISI-S was founded with the aim of bringing together intelligent individuals who also value creativity."