libxmp is a module player library which supports many mainstream and obscure module formats, including Protracker MOD, Scream Tracker III S3M, and Impulse Tracker IT. Possible applications for libxmp include standalone module players, module player plugins for other players, module information extractors, background music replayers for games and other applications, module-to-mp3 converters, etc.
Metakit is a small, portable database library using a hybrid relational / hierarchical data model with a column-wise internal storage format. For C++, include a single header file and 125 kb DLL or statically link directly. Ideal for desktops, embedded systems, smartphones, and PDAs. Bindings for Python and Tcl. A very mature, stable code base.
DSFoundation is a foundation enhancement library for Objective-C. It includes an IOC (Inversion of Control) container, translation (serialization and conversion) to and from Objects, YAML, and XML, automatic KVC adaptation and compliance, logging through an integrated Log4Cocoa, regular expression extensions, and much more.
Fluxfont is a specialized tool that attempts to tackle the privacy concerns raised by the possibility to collect information about the fonts installed on a system. Such information can be used to uniquely identify a system. With Fluxfonts, new fonts are randomly created and removed to prevent the same fingerprint from being recreated.
Changing directories in bash can be tedious if you have long names or nested paths. Creating aliases or adding to the CDPATH can help, but can be improved on. Bashcd adds 6 new commands to make changing directories a bit easier. This commands use find, the locate database, the mdfind database, or other contextual information to make it easier to change to other directories.