GigPress is a live performance listing and management plugin that's been serving musicians and performers since 2007, when I "learned" PHP in order to write it. This shows in the procedural mess that is the code.
Lack of available time and my decreasing use of WordPress have led me to neglect the poor thing in recent years, although I do try to keep up with bug fixes. Perhaps some brave souls here in GitHub-land who are still avid users will endeavour to improve it!
The plugin is officially hosted on WordPress' plugin repository (which is a Subversion repo) - hence the plugin directory being named trunk. If you are downloading from here on GitHub, simply rename trunk to gigpress.