I’m in the process of updating the OPML Support for Firefox extension; I’ll be adding bookmark import/export to complement the Livemark support already there. Additionally, since the extension will have features that don’t require Livemark support in the browser, I’ll be making it compatible with browsers other than Firefox (depending on how much the bookmarking API differs from Mozilla to Firefox to Netscape to Seamonkey).
So while I’ve got my hands dirty and the code is fresh in my mind, are there any feature requests? Feel free to leave them in the comments or e-mail me directly.
One thing I’m especially looking forward to is that once this version is done, you’ll be able to use OPML to backup your bookmarks just like Firefox’s built-in bookmark import/export, but without all of the cruft. There’s nothing like adding a freshly exported (valid) XML file to your folder of bookmark backups.