Computer Programs for Pure Mathematicians Question: Which computer programs are useful for a pure mathematician to familiarize themselves with?
Less Briefly: I was once told that, now-a-days, any new mathematician worth his beans knows how to TeX up work; when I began my graduate work one of the fourth year students told me he couldn't TeX, I was horrified!  Similarly, a number of my peers were horrified when I told them I'd never used Matlab or Mathematica before.  Currently, I can "get by" in all three of these programs, but it made me think: what programs are popular with pure mathematicians?  I don't mean to limit this to computing things: programs which help to draw pictures and things can also be included.
Lest I Start A Flame War: This is not meant to be a "what is your favorite computer language" question or a poll on who thinks Mathematica is worse than Sage.  This is meant to be a survey on what programs and resources are currently being used by pure mathematicians and may be good to look at and read up on.  
I'm also unsure of how to tag this.

mpmath, which is a part of sage has great special functions support.
nickle is good for quick things, and has C like syntax.
