Currently supported languages: Python, Octave, Ruby (linux only), C, C++
If you want to make serious changes to TinkerCell and like C++, read this document.
If you want to create quick scripts and automatically share it between other TinkerCell users, read this document.
TinkerCell will automatically install these plugins and keep them up to date using Subversion. Subversion is included with the TinkerCell Windows installer; Mac and linux systems generally have Subversion preinstalled, or it is easy to install using apt-get.