The Mediawiki Pipes extension implements external data access and processing through a series of configurable nodes that form a Pipe. The net effect is to create a Wiki based application framework. See http://www.mediawiki.org/wiki/Extension:Pipes1 weekly downloads
Hawi is a web-based geographic wiki used for mapping places that are interesting or encyclopedic. Hawi runs on LAMP and uses the Google Maps API. Hawi is licensed under the GPL and is freely available for anyone to use.