Here are some of the programs that I use.
Luxology Modo – A complete 3D computer graphics program that specializes in subdivision surface modeling.
Pixologic Zbrush – 3D modeling package with lots of innovative features. Wonderful for organic sculpting.
Newtek LightWave 3D – Another 3D computer graphics program. Great for animation.
Adobe Photoshop – Great for image editing and digital painting. This is a must have for a lot of creative industries.
Filter Forge – A plugin for Photoshop that creates procedurally based tiling textures. Great for digital sculpting and texture work.
ACDSee – A photo and video editing program that specializes in quickly renaming, resizing, and organizing lots of picture and video files at once.
Unreal Engine 4 – A next gen video game engine with a quickly growing feature set, community, and documentation.
Wacom Tablet – A great input device for digital painters and sculptors.
Sony Vegas – Video and audio editing program.
Libre Office – A free word processing program that is complete with spreadsheets and slideshows.
Raw Therapee – This program is a free alternative to Adobe Lightroom.
Hugin – Stitch your panoramas together for free. Sometimes it’s a bit buggy.
Alchemy – A random 2D shape generator. Produces images that a psychologist might use to diagnose a patient, but artists can use it to get inspiration.
Freemind – Create mental maps of your thoughts in a visual way. It is programmed with Java, so the maps are easy to export to a number of formats.
Quickman – Good 2D Mandelbrot set generator. You can customize the colors and render images and movies.
Mandelbulb 3D – This 3D fractal program is easy to learn, has a huge community, and the fractals can be exported to polygonal objects.
Fiji/ImageJ – Use this program in conjunction with Mandelbulb 3D to import the fractals into your favorite 3D graphics program.
7-Zip – Free program that can compress and decompress zip files.