I like working on open source projects. Here is a few that I've either started or contributed a significant amount of work to.
- AcoustID - Audio fingerprint database with free audio identification service
- MusicBrainz - Open music metadata database
- TagLib - C++ library for reading/writing metadata in audio files
- Database Modeller - Simple GUI tool for drawing entity-relational diagrams
- All Pull Requests - Plugin for Atlassian Stash with a project-wide pull requests view
- python-phoenixdb - Phoenix database adapter for Python