This is a list, in no particular order, of digital art and design software that I use/have used within my practice/study/spare time.
Free: Pencil: http://www.pencil-animation.org/
Animation software leaning towards hand-drawn animation styles.
Free: Rasterbator: http://rasterbator.net/
Software that separates and simplifies images into sections that can be printed out and put together to make a large colour/b+w/monochrome poster.
Free: Sculptris: http://pixologic.com/sculptris/
Free simplified version of Z-brush. A 3D sculpting software that can be used to produce concepts or fully fleshed out models
Requires purchase: Spine: http://esotericsoftware.com/
Animation software that allows you to create skeletons/spines to attach image sections and create animation patterns and cycles.
Free: Stereo Photo Maker: http://stereo.jpn.org/eng/stphmkr/
3D Anaglyph/Stereoscopic image software, used to create 3D images from a left and right image. Can produce gifs that do not require glasses
Free: Blender: http://www.blender.org/
Powerful open source 3D modeling software, strong community and many tutorial resources and plug-ins.
I will add more to this list in the future