From http://web.archive.org/web/20150223210813/http://schemewiki.org/

SchemeWiki.org is run by Schematics. The main project hosted here right
now is the Scheme Cookbook.

Scheme Wikis
Here is a list of wikis which are either Scheme-related, or implemented
in Scheme, or both.

Schematics Scheme Cookbook - Practical documentation for using Scheme
(PLT-oriented)
MoshiMoshi Wiki - Wiki implemented in PLT Scheme
Scsh Wiki - Wiki for scsh, the Scheme Shell, implemented in scsh
SISC Wiki - Wiki for SISC Scheme
WiLiKi - WiLiKi is a wiki implemented in Gauche Scheme
CommunitySchemeWiki (CSW) - A general-purpose wiki for the Scheme
community, running on WiLiKi
Scheme Cross Reference - A directory of Scheme syntax, procedures, and
variables found in various Scheme implementations
Chicken Scheme Wiki - The wiki for Chicken Scheme, the practical and
portable scheme system.