I know the install programs for them used to import each others bookmarks but I was wondering if there was a good standalone interactive tool that would do something like a DIFF and then offer to create or remove the links.

I've used IE Converter to do conversions before, but it's not command-line or anything. Worked well for me just to convert once, not to maintain bookmarks in both places.

Well that's a start, at least it goes one direction. I wonder if I could find what I'm looking for in some scripting language cookbook.

Well, it turns out this functionality is already built into IE (probably since 4.0). I actually went to the help in IE and found this. What a concept.

But it's still not totally automated. Maybe I will make a personal project to make this happen in the background somehow like have it run a script to generate a bookmark.htm from favorites when you logoff and do the opposite when you log on.

I keep my bookmarks in XML format, and then use it as my homepage. With a bit of XSLT and CSS, it comes up looking quite nice.

The advantage is that it works in every recent browser I've tried, and I can get to my bookmarks from anywhere, including Internet cafes.