Nomenclature package allows you to include lists of the used
symbols in LaTeX documents (now the development is taken over by CV
Radhakrishnan and Lee Netherton).
EnvLab package typesets envelopes and labels for mailing.
KOI-8 package (written mostly by Uri Blumenthal) is intended for
typesetting Russian texts.
FoilHTML package supports integration FoilTeX system and LaTeX2HTML.