GIMP is an open source program for editing and developing of bitmap graphics.  
It is freely distributed and intended only for correction and retouching of photographs, bitmap painting and drawing, and editing and preparation of bitmap printing graphics. It resembles Adobe PhotoShop in many options it has, and supports almost all graphic programs and conversions from one format to another. GIMP is mostly used for preparation of digitalized graphics for web, especially picture galleries and visual identity development.

WEB: http://www.gimp.org

Jahshaka is an open code program primarily for development and processing of video materials. In addition to a click and develop interface, it also enables simple editing of raw video materials, adding new object as textual recording (useful when creating telop), adding objects in 3DS format made in well known 3D object and animation development program, 3D studio Max,...

WEB: http://www.jahshaka.org

Audacity is an extremely powerful and stable sound editor and recorder. It also converts different formats,  applies filters in virtual real time, supports working with great number of sound cards, reproduces well the sound filed. This is a good tool for a user who needs good quality digital sound with simple interface.

WEB: http://audacity.sourceforge.net/

Sodipodi is a program for vector drawing and vector elements manipulation similar to programs such as Adobe Illustrator or Macromedia Freehand. The interface reminds of GIMP interface – the tools and the documents are in separate windows, which facilitates working with many tools and improves the layout. The tools are set to standard, but there is a possibility to manually adapt the work surface and save the settings. Working files are saved as SVG format, but extraction of document in the form of a bitmap image in PNG format is also possible. Importing and exporting into PDF format requires an installation of PDF writer or a similar program. Very good quality PDF files are obtained.

WEB: http://www.sodipodi.com

Open source tools for modelling and development of 3D animations. It is currently distributed as 2.25. version. You can select a standard package which includes the complete program, but it is also possible to install an additional program Blender publisher, which offers a supplement for extracting working elements in web formats, and they are powered by an independent program capable of reproducing them.

WEB: http://www.blender.org