Astronomers will also find TeX and LaTeX Macros for astronomers from STScI to be useful. Particular helpful is Chris Biemesderfer's LaTeX Command Summary.
A TeX and LaTeX FAQ is available from Emory Univ.
An ascii verison is available from Ohio State.
Hypertext information similar to the current set of files also originated from VMS help files.
Text Processing Using LaTeX from Cambridge Univ. Engineering Dept. includes an excellent hypertext manual.
A good hypertext Intro to LaTeX is from a short course at Rice Univ.
Another good hypertext discussion of Document Preparation with LaTeX comes from the Univ. of Sterling, UK.
A Guide to LaTeX from Univ. of Alberta is introductory and I've spotted mistakes.
Aspects of publishing with TeX and LaTeX is an introduction to the philosophy of TeX and LaTeX.
Lots of documentation, mostly PostScript, is available from King Lee at Calif. State Univ., Bakersfield, or an alternate link.
LaTeX documentation, from UCLA, also mostly (compressed) PostScript files.
Tex-related documents from Cambridge Univ.; includes TeX Users Group newsletter and many documents (mostly in dvi format).
LaTeX2e Documentation from DESY is mostly PostScript.
Pointers to many European TeX resource are available from bluesky.com (just in case you need to hyphenate Nordic languages or want to typeset in Hebrew).