Image, Office suites, and other general purpose software
If you are using Linux, changes are that this page is not that useful for you, since most of these programs come installed by default. For you who are not yet into linux, most of these programs have Windows/Mac versions:
Office suites (spreadsheet calculation, slide manufacturing , document writing):
Image manipulation programs (vectorized images or photoshop style):
3D modelling (to create animations, solids or even things that can be printed):