Mup produces very high quality PostScript printed music or a MIDI file from a text input file. It can handle almost any kind of music, instrumental or vocal, including tablature, shaped notes, guitar grids, alternate tunings, user-defined symbols, and much more. Mup has been under active development since 1992.
Minnow is a concurrent programming language with a Ruby-like syntax. It compiles to an executable and uses a companion library to allow fully-rebalanced microthreads. Minnow gains a lot of strength from its actor model, which uses message passing, as opposed to threads and locking, as its concurrency model. Taking a cue from Erlang, actor creation and message passing is extremely lightweight (often on the order of a few nanoseconds). The language has a built-in foreign function interface that allows developers to leverage existing C-based libraries in a simple SWIG-like manner. Minnow's object model is based on "melding" features together to form objects.
DromeAudio is a small audio manipulation and playback library. It features a simple API for loading, generating, processing, and playing audio. Some of its features include loading and saving WAV sounds, loading Ogg Vorbis sounds, audio mixing/playback, and dynamic audio processing effects such as pitch shifting and echo.
libpwstor is a library implementing a password storage format for C programmers. This format provides a reasonable level of security by utilizing SHA-256 in addition to a random salt to mitigate dictionary and rainbow table attacks. In addition to the core functionality, libpwstor also offers some additional functions such as Base64 encoding and decoding. All functionality is implemented and designed in such a way as to be easy to use for C programmers of varying skill levels, while preserving reasonable security in the underlying storage format.