probably a dumb question, but you know me...RTF output

It would require some custom programming, but we could do it. You can read about the rtf format on wikipedia here: http://en.wikipedia.org/wiki/Rich_Text_Format

Here's some sample rtf code (from wikipedia):

{\rtf1\ansi{\fonttbl\f0\fswiss Helvetica;}\f0\pard
This is some {\b bold} text.\par
}

A quick google search shows there seems to be some PHP libraries out there for converting HTML to PDF. It seems to encompass things like page margins and other information that wouldn't be in the html though.

You might find out what the client wants the RTF for. You might be able to get away something as simple as opening an html document from Word or Open Office. I bet both of them would import it. I did a quick test with my local copy of Word 2002 and I was able to open "http://www.interactivetools.com/" and save it as RTF with no problems.

Hope that helps, let me know if you need more details about any of that.