FWIW, my collection of links etc. may be found at the top of planetscape's extra scratchpad.
Update 2006-06-10: Or, better, inline here, in case I later forget and delete/move something...
Clean up your Web pages with HTML TIDY
HTML Tidy Library Project
Charlie's Tidy Add-ons, including a Perl Wrapper
HTML tidy, using XML::LibXML
Demoronizer - A perl script to sanitize Microsoft's HTML
Demoronizer - Correct Moronic Microsoft HTML
Word HTML 2 Formatting Objects
WH2FO is a Java application that processes an HTML output, created with Word 2000, and transforms it into an XML content file and an XSL stylesheet file. From these files, a standard XSLT processor may be used to obtain a file containing only XSL-FO markup. You can also apply a stylesheet that converts the XML back into HTML discarding all the extra markup added by Word. Using an XSL-FO renderer, such as FOP, you can also render your document into PDF.
GrandFather's PerlMonks Editor - on CPAN: PMEdit-001.000104-1.pl
HTML::Parser has several example programs, such as hstrip.pl which might be helpful
OpenOffice.org - free office suite and MSOffice alternative
Use OpenOffice to save in HTML format. OpenOffice creates much cleaner HTML, and the resulting file may still be run through HTML Tidy or a script such as hstrip.pl.
Word Processor Filters