Tiddlyweb-plugins is a project mainly written in ..., it's free.
Plugins for TiddlyWeb
This directory contains a collection of TiddlyWeb plugins. Some are quite mature, others less so. Most have a README explaining their state.
These plugins may be of use, either to use directly or as examples of techniques to use when creating your own plugins.
Plugins that have reached a reasonable level of stability have been packaged and are distributed from PyPI:
http://pypi.python.org/pypi?%3Aaction=search&term=tiddlywebplugins
Some plugins now have their own repositories on GitHub, have a browse of
http://github.com/tiddlyweb
Look to http://tiddlyweb.com/ for more information.