Very fast and versatile 3D modeller/renderer

blender

Very fast and versatile 3D modeller/renderer

Blender is an integrated 3d suite for modelling, animation, rendering, post-production, interactive creation and playback (games). Blender has its own particular user interface, which is implemented entirely in OpenGL and designed with speed in mind. Python bindings are available for scripting; import/export features for popular file formats like 3D Studio and Wavefront Obj are implemented as scripts by the community. Stills, animations, models for games or other third party engines and interactive content in the form of a standalone binary are common products of Blender use.
3D arcade racer with a variety of characters, tracks, and modes to play

supertuxkart

3D arcade racer with a variety of characters, tracks, and modes to play

Karts. Nitro. Action! SuperTuxKart is a 3D open-source arcade racer with a variety of characters, tracks, and modes to play. The aim is to create a game that is more fun than realistic, and provide an enjoyable experience for all ages.
real-time photo-realistic sky generator

stellarium

real-time photo-realistic sky generator

Stellarium renders 3D photo-realistic skies in real-time. With Stellarium, you really see what you can see with your eyes, binoculars or a small telescope.
Sophisticated CD/DVD burning application

k3b

Sophisticated CD/DVD burning application

K3b is a full-featured CD/DVD/Blu-ray burning and ripping application. It supports a variety of project types as well as copying of optical media, burning of different types of images, and ripping Audio CDs, Video CDs, and Video DVDs. Its convenient user interface is targeted at all audiences, trying to be as simple as possible for novice users, while also providing all features an advanced user might need.
Kodi Mainscreen

kodi

Open Source Home Theatre (executable binaries)

Kodi, formerly known as XBMC is an award winning free and open source software media-player and entertainment hub for all your digital media. Kodi is available for Linux, Mac OS X (Leopard, Tiger and Apple TV) and Microsoft Windows, as well as the original Xbox game console. Created in 2003 by a group of like minded programmers, Kodi is a non-profit project run and developed by volunteers located around the world. More than 50 software developers have contributed to Kodi, and 100-plus translators have worked to expand its reach, making it available in more than 30 languages.
Calibre is meant to be a complete e-library solution. It includes library manage

calibre

powerful and easy to use e-book manager

Calibre is a complete e-library solution. It includes library management, format conversion, news feeds to e-book conversion, e-book viewer and editor, and e-book reader sync features.