In 1996, the idea arose to have a group called "Giga Society" for candidates scoring at or above the level of one in a billion on high-range intelligence tests, to encourage people to take the tests and thus collect data for norming and research. This was made known in personal correspondence, information included with score reports, and in articles in I.Q. society journals like OATH, In-Genius, and Thoth. Below is a non-exhaustive list of publications from the 1996-1999 period that mention the Giga Society as such; these serve as proof that the name "Giga Society" (or "The Giga Society") has been in use in the context (scope, namespace) of I.Q. societies since that time. Although the concept of the Giga Society originates in Paul Cooijmans, it has always been the intention to accept sufficiently high scores on tests by other constructors too, if those meet the society's stringent criteria.
After the second enrollment, in 1999, that member (Thomas Wolf) created a web site for the Giga Society at gigasociety.org, which existed until April 2004 at least and can still be seen using the Internet archive. It had two guestbooks during its existence, and the entries of the second guestbook (2001-2004) have been saved and are provided on the present Giga Society web location.
Darryl Miyaguchi's web site, Uncommonly difficult I.Q. tests, has mentioned the Giga Society since the late 1990s and referred to its subsequent web sites since 2000, as can still be seen at miyaguchi.4sigma.org .
Bill Bultas' web site puzz.com has likely mentioned the Giga Society in the late 1990s and early 2000s, but this can not be verified currently.
From early 2001 onward, Paul Cooijmans maintained a web page devoted to the Giga Society as part of his personal web location, which (the page) would later (January 2009) become gigasociety.com .
From 2003 or 2004 onward, Evangelos Katsioulis had a Giga Society web site at giga.iqsociety.org for a number of years that existed alongside Paul Cooijmans' page. The logo of this site by Katsioulis would, in 2021, be stolen by an impostor who used it for a fake Giga Society web site, which he (the impostor) started in June 2021 after learning he did not qualify for the actual Giga Society.