The MathOverflow question Open source mathematical software contains a list of programs that are useful to perform various computational tasks, such as computer algebra systems.
However, evaluating complicated formulas is not all that a professional mathematician needs to do. For instance, another important part of it is communicating results, producing papers and slides. There was a Mathoverflow question devoted specifically to tools for collaborative paper writing.
It would be useful to identify and gather on MO a list of areas of activities where research mathematicians can use software as part of their professional activity.
I think it would also be useful to gather on MO a list of software that does not strictly do computations, but is nevertheless useful to those who research and teach mathematics.
The first example that springs to mind is of course $\LaTeX$, but there is much more:
- citation and literature management software, such as Jabref, Zotero, Mendeley
- conference management software, such as Open Conference Systems (never actually used it, but it seems interesting)
- reference tools such as the Online Encyclopedia of Integer Sequences and Plouffe's Inverter
- Euclidean geometry software such as Geogebra
- diff'ing and merging tools, such as latexdiff, kdiff3
- specific LaTeX packages such as Beamer for presentations or several drawing packages (TikZ, Eukleides).
I find some of those real gems, and I'd like to find out more examples. So, the question is:
Can you provide (other) examples of programs that are useful to professional mathematicians in their job, while not being strictly speaking "software that does complicated computations"?
The question is a little broad and perhaps if there is much software relevant to a specific activity it will be wise to ask, based on input given to the question, a more specific question. Also please do not interpret this question too broadly (see discussion below).
Also check these MO questions: Tools for collaborative paper-writing (mainly regarding revision control software), Most helpful math resources on the web (mainly regarding online databases of something).