centericq is a text mode menu- and window-driven IM interface that supports the ICQ2000, Yahoo!, AIM, IRC, MSN, Gadu-Gadu, and Jabber protocols. It allows you to send, receive, and forward messages, URLs, SMSes (both through the ICQ server and email gateways supported by Mirabilis), contacts, and email express messages, and it has many other useful features. An internal RSS reader and a LiveJournal client are also provided.
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.
BitlBee allows users to talk to people on the major instant messaging and microblogging networks (including MSN, Google Talk, AIM, and Twitter) from within any IRC client by emulating an IRC server. Virtual channels are created with all of the user's contacts in them, who can be talked to in the channel or in a query. Also, one can participate in group chats and chat rooms like they were normal IRC channels.
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.