Audacity is a free, open-source music/sound editor/viewer. It has many features, such as normalization, Equalization, and Echo. It has a very simple and intuitive GUI interface.
Audacity can be used for a plethora of things, such as volume raising, and sound clipping. It can also open a good amount of file formats and export them as many different formats.
Audacity can be extended to do other things, using plugins. It is very easy to add and use these plugins.
To install the plugins, download a plugin that you like, and under the Installation directory, copy the plugin into the Plug-Ins folder.
|2D||Microsoft Paint - GraphicsGale - Adobe Photoshop - Paint.Net - GIMP|
|3D||Autodesk 3DS Max - Autodesk Maya - Blender - Cinema 4D - Milkshape 3D - Anim8or|
|Sounds||Adobe Audition - Audacity|