Automatically creating plain text alternative to html email

[docgnome <docgnome@gmail.com>]

Hi,
The subject basically says it all. Does anyone know of a way to
automatically create a plain text alternative to an html message? I'd
like to be able to send multipart messages because I need to use html
for my work signature, but I would like to give those using text based
MUAs and those using screen readers a reasonable representation of
the data.
Cheers,
Dave