GNU Octave - a high-level language, primarily intended for numerical computations. Very much like MATLAB, but GPLed.
GNU Octave at Wikipedia
The Octave FAQ had a neat BibTeX reference:
author = "John W. Eaton",
title = "GNU Octave Manual",
publisher = "Network Theory Limited",
year = "2002",
isbn = "0-9541617-2-6"
Which got me thinking about how I'm going to deal with references in my M.Sc. and beyond. I'm thinking about BibTeX:
BibTeX at Wikipedia
Which then led me to think of how I would do this in Emacs and texinfo.
BibTeX at emacswiki
Ebib is a program for managing BibTeX databases.
BibTeX and Emacs at lyx wiki.
BibTeX - emacs mode
Planner mode from a bibtex buffer (I use Planner Mode in Emacs constantly)
RefTeX - provides distinct support for doing labels, references and citations in LaTeX.