LaTeX has established itself as the most widely used specialist Mathematical typesetting language, and learning at least the basic will be very useful for anyone considering studying Mathematics at a higher level. All of the documents in the Work and Puzzles section of this site are written in LaTeX. I have listed here some basic links to get you started.
LaTeX Project homepage  Has all the basic documentation to get you started (read the NotSoShort Introduction at least once!) and details on where to get the software.
LaTeX Community Forums  I haven't used this extensively, but it looks like it could be useful for troubleshooting/advice.
