Make your own quadrille, graph, hex, etc. graph paper. Uses the pgf/TikZ package for LaTeX, which should be part of any modern TeX installation.

Detexify is a simple web-based app for automatically finding LaTeX commands for any symbol drawn by the user. It uses a machine learning algorithm to predict the most likely symbol.

A handy website with LaTeX commands for creating math symbols, Greek letters, and more.

SEGTeX is a LaTeX package for geophysical publications. It consists of
- LaTeX2e class files for Geophysics papers, SEG expanded abstracts, etc
- BibTeX style files seg.bst
- BibTeX cumulative bibliography of geophysical publications SEG.bib
- latex2html customizations.