ergophobe - 7:40 pm on Dec 14, 2010 (gmt 0)
What about various types of filtering? There are some add-ons/plugins/modules like Beautify and things like that to clean up HTML after the fact and filter out tags and attributes as needed.
In Drupal you can also turn off a lot of the features for TinyMCE. Not sure about other CMS.
Of course, then the client might say "But now I can't make tables. I need tables" or whatever it is you're filtering out, and you'll be stuck.