Frescobaldi is a LilyPond sheet music editor with built-in MIDI player and PDF preview. It aims to be powerful, yet lightweight and easy to use.
Enc2ly is a small tool for dumping musical information contained in an Encore binary file to a Lilypond text one. Encore is a popular music notation program from GVOX which uses a proprietary data format. Lilypond is a great music engraving system.
A GUI toolkit for Linux and Android.
A command scheduler for non-permanently-running systems.