Thunderbird is a total redesign of the Mozilla mail component to produce a cross-platform, stand-alone mail application using the XUL user interface language. It has many new features, among them the ability to customize your toolbars the way you want them. a new look and feel with a large number of downloadable themes which alter the appearance of the client, and the ability to add UI extensions.
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.
Roundcube Webmail is a browser-based, multilingual IMAP client with an application-like user interface. It provides the full functionality you expect from an email client, including MIME support, address book, and folder manipulation. High extensibility is granted by the plugin API and the user interface is fully skinnable using XHTML and CSS 2.
Chamilo is an e-learning and collaboration platform. Chamilo is currently used by more than 7,000,000 students around the world. Governments, private companies, public and private universities, NGO, and other types of organizations use the Chamilo software suite to manage activities from simple live training to full distant learning, certification, and staff selection.
Pybik is an interactive, graphical, single player puzzle about the cube invented by Ernő Rubik. Besides the cube, the program can handle towers and bricks (non-cubic puzzles). Pybik also has solvers, pretty patterns, and a collection of various moves. The cube can be manipulated with the mouse or keyboard. You can change the colors or images on the faces of the cube.