GLPI (Gestion Libre de Parc Informatique) is an information resource manager with an administration interface. You can use it to build a database with an inventory for your company (computers, software, printers, etc.). It has functions to make the daily life of the administrators easier, including a job/request tracking system with mail notification and methods to build a database with basic information about your network topology. It provides a precise inventory of all the technical resources (all their characteristics are stored in a database) and management and history of the maintenance actions and the bound procedures. It is dynamic and is directly connected to the users, who can post requests to the technicians.
MuseScore lets you notate and compose music easily with your keyboard, your mouse, or a MIDI keyboard. You can print beautifully engraved sheet music or export it as PDF or PNG. You can play your score, transpose it, and save it as audio or MIDI file. MuseScore also supports MusicXML to let you share your composition with other scorewriters. MuseScore is often advertised as a cost effective alternative for Sibelius and Finale.
Psensor is a graphical hardware temperature monitor for Linux. It can monitor temperatures of the different hardware sensors (motherboard and CPU using lm-sensors), hard disk drives (hddtemp/libatasmart), and ATI/Nvidia GPUs. The fan can also be monitored (lm-sensors). Psensor is designed to be simple and easy to use.
Zina is a graphical interface to your MP3 collection, a personal jukebox, a Podcaster, and an MP3 streamer. It includes an optional Flash player, a tag editor, and can search the Web for album art and song lyrics. It can run alone, be embedded into an existing Web site, or be used as a module in Drupal, Joomla, and Wordpress.
Nyagua is a little piece of software that may help you to manage your home aquarium. It can store data about measurements in aquariums and produce graphs from these. It can store data about expenses and produce a report with yearly, monthly, and daily costs. It reports the compatibility between fishes and plants in its database. It can import fishbase.org XML data, and your own pictures can be added.