PidginTeX plugin for the instant messaging client Pidgin and 
uses mimeTeX or mathTeX to render LaTeX expressions in messages 
and chat. It is intended for math but mathTeX is fully compatible
with LaTeX and any package can be used and mimeTeX also supports 
many other features.

The syntax is simple, write $$latex expression$$ anywhere in a 
message and an image will appear in the message log.

This requires mathtex.