OK, it sounds like this project is a bit abandoned.

Nobody seems to care.
http://drupal.org/node/46726

But I've got useful things to add.

- Reworked a lot to enable use as an input validator
and an output filter, as well as the original site-wrapper.
- Added a test and install function to help ensure the HTMLTidy
executable is present.
- Configured so it can optionally use an external tidy.conf file,
and so make use of all the HTMLTidy options. (like clean Word2000)