Haru is a free, cross platform, open-sourced software library for generating PDF written in ANSI-C. It can work as both a static-library (.a, .lib) and a shared-library (.so, .dll).
VocalEasel is a simple lead sheet editor and music rehearsal tool designed for the needs of Jazz vocalists, using LilyPond to produce printable lead sheets and MMA (Musical Midi Accompaniment) to produce MIDI accompaniments.
The Fury² Game Creation System is a game development toolkit for the 32-bit Windows platform, designed to allow the creation of complex multimedia software and games with minimal unnecessary effort (i.e. reinventing the wheel.)
The XML Code Template Engine produces class code skeletons that can include equality and logging methods in C++ or Java(so far) from an XML document outlining. It also creates Doxygen compatible comments and a has very simple plugin system.
tcom is a specification and implementation of a distributed component system which uses tuple spaces for IPC. Components can be written in any language. tcom is also well suited to modular apps which run on a single machine.