Gimp User Filter is a work-alike to Adobe's Filter Factory. It is a generic image processing plug-in that can be used to create new filters for The GIMP without having to go through the process of learning about The GIMP's SDK. Many freely available filters that have been created for Filter Factory can also be used with this plug-in.
Mutabor is a program that allows you to perform and compose microtonal music using a normal MIDI keybord and normal MIDI equipment. Its powerful description language is intended to allow permanent retunings and complex tuning logic. One application is just tuning. Mutabor has been used for this purpose to make available all pitches that can be reached by stacking perfect thirds and perfect fifths. The stable version 3.0x is available in German only and runs under Windows and Wine. The unstable branch can be accessed via CVS (but build bugs should be expected) or downloaded from the Berlios developer site.
TXR is a new data munging language to replace the likes of awk and Perl. TXR's special pattern language provides template-based matching of entire documents or large sections of documents. It also contains a language for functional and imperative programming. It is written in C and takes the form of a utility that is portable to Unix-like platforms and Windows.
foma is a compiler, programming language, and C library for constructing finite-state automata and transducers for various uses. It has specific support for many natural language processing applications such as producing morphological analyzers. Although NLP applications are probably the main use of foma, it is sufficiently generic to use for a large number of purposes. It comes with an xfst-compatible interface and regular expression language. The library contains efficient implementations of all classical automata/transducer algorithms: determinization, minimization, epsilon-removal, composition, and boolean operations. More advanced construction methods are also available: context restriction, quotients, first-order regular logic, transducers from replacement rules, etc.