I had problems like this when I was dealing with (i.e. figuring it out to
document it) a firewall. The firewall came with a large menu of MIME
types, many of which I'd never seen, but admins had to add new ones by
hand. text/xml and application/xml are the least of the problems to be
faced; think of all the new types that will come out of standards built on
XML.
Hmm... maybe it's worth an article.
Simon St.Laurent
Dynamic HTML: A Primer / XML: A Primer
Cookies / Sharing Bandwidth (November)
Building XML Applications (December)
http://www.simonstl.com