I'm currently using the Xmarks type of add-ons, but Xmarks is planning to shut down within 90 days, and no replacement seems to be available. Although Internet Explorer 8 is my preferred browser, add-ons to eliminate duplicate bookmarks appear to be available only for Firefox. Also, I can report newsgroups spam fast enough on Google Groups that their software often confuses me with a computer program; rotating among the four browsers I have installed seems to help with this. I'd like to synchronize the bookmarks collection among all 4 browsers; the Xmarks series of add-ons currently does this with two of them, and tries but fails with a third one; not available for the fourth.