Implemented in R5RS (see RevisedReportOnAlgorithmicLanguageScheme).
LukesProgrammableWiki is programmed in ErlangLanguage, which in turn implements SchemeLanguage as an embedded language for end-user code. So it is the first user-programmable SchemeWiki. -- FridemarPache
WiLiKi (http://www.shiro.dreamhost.com/scheme/wiliki/wiliki.cgi) is another Scheme wiki project, implemented in Gauche (an R5RS Scheme implementation developed to be a handy script interpreter, which allows programmers and system administrators to write small to large scripts for their daily chores ... http://www.shiro.dreamhost.com/scheme/gauche/).
Resources
-Applications
End-user applications written using Scheme:
Libraries and modules for use in Scheme (but not SchemeImplementations or end-user applications):
Sites that contain directories of libraries and modules:
Wikis to discuss Scheme