Ling-Tex: there is a mailing listling-tex@ifi.uio.no for
linguist-users of TeX and LaTeX, and an associated
web page
which contains lots of useful information.
There is an inventory of LaTeX tools etc. for dealing with linguistic
structures due to Ch. Thiele. It is somewhat dated (last update 1994), but still
very useful. It can be found in the standard CTAN archives, (e.g.
http://www.tex.ac.uk/, in http://www.tex.ac.uk/info/ling-mac.tex).
It is also available here, in various formats.
the Institute of Formal & Applied Linguistics of Charles University
Prague maintains a list of LaTeX packages relevant for linguists:
http://kwetal.ms.mff.cuni.cz/~gj/latex.html.
LaTeX for Logicians: while not specifically about linguistics, LaTeX
for Logicians contains much useful information (e.g. about type setting Natural
Deduction proofs, as used in Categorial Grammar):
http://www.phil.cam.ac.uk/teaching_staff/Smith/LaTeX/.