Armadillo is a C++ linear algebra library (matrix maths) aiming towards a good balance between speed and ease of use. The API is deliberately similar to Matlab's. Integer, floating point, and complex numbers are supported, as well as a subset of trigonometric and statistics functions. Various matrix decompositions are provided through optional integration with LAPACK and ATLAS numerics libraries. A delayed evaluation approach, based on template meta-programming, is used (during compile time) to combine several operations into one and reduce or eliminate the need for temporaries.
Linphone is an audio and video Internet phone with GTK+ and console interfaces. It uses the SIP protocol, and is compatible with most SIP clients and gateways. It can use various audio and video codecs such as Speex, GSM, G711, G722, ilbc, amr, Theora, H263-1998, MPEG4, H264, VP8, and snow.
The "Schily" Tool Box is a set of tools written or managed by Jörg Schilling. It includes programs like: cdrecord, cdda2wav, readcd, mkisofs, smake, bsh, btcflash, calc, calltree, change, compare, count, cpp (K&R original), devdump, hdump, isodebug, isodump, isoinfo, isovfy, label, mt, p, patch, sccs, scgcheck, scpio, sdd, sfind, sformat, smake, sh (Bourne Shell), star, star_sym, suntar, gnutar, tartest, termcap, and ved.
BORG is a calendar and task tracking system written entirely in Java. The calendar is an appointment organizer that provides a nice month view, month printing, email reminders, popup reminders, and a to do list. The task tracker tracks issues and tasks through various user-defined states.
4tH is a Forth compiler with a little difference. Instead of the standard Forth engine it features a conventional compiler. 4tH is a very small compiler that can create bytecode, C-embeddable bytecode, standalone executables, but also works fine as a scripting language. It supports about 95% of the ANS Forth CORE wordset and features conditional compilation, pipes, files, assertions, forward declarations, enumerations, structures, suspended execution, recursion, include files, etc. It comes with an RPN calculator, line editor, preprocessor, compiler, decompiler, C-source generator, a virtual machine, and a multitasking environment.
Audacity is a cross-platform multitrack audio editor. It allows you to record sounds directly or to import Ogg, WAV, AIFF, AU, IRCAM, or MP3 files. It features a few simple effects, all of the editing features you should need, and unlimited undo. The audio I/O uses PortAudio, which fully supports OSS, Mac OS X CoreAudio, and Windows WMME, and can be compiled with support for ALSA and Jack.