I'm looking for a good bookmark manager too. Tried a few lately, and they all seem bloated, awkward to use and using too many resources (for constant use) and even expensive.
But then I found "Bookmark-Manager" that is free and open source and seems to use less resources. Runs conveniently in the system tray, sports a floating bookmark toolbar (which behaves a bit buggy here). Not too pretty looking, but it does quite a fine job of synchronizing bookmarks between all the browsers, though this is rather an awkward task (as in all bookmark managers). I think, I'll stick with this one. Maybe give it a try. You need the vbBKM version for a Windows operating system.
http://bkm.sourceforge.net/