Wiki converters

There are a number of useful utilities for converting various document and HTML formats to MediaWiki, and vice versa.

Converting documents to mediawiki markup
Mediawiki editing tools
HTML::Wiki Converter -- a nice online converter
Word-to-HTML works for files up to 20 KB; subscription needed for larger files or frequent use
The Clean MS Word HTML Page open source project does much the same thing; paste in Word content, click the Clean button, then get your purified HTML that you can paste into the raw HTML tab of your blog post editor