Previously a Firefox-only add-on, Foxmarks (which is soon to get a new name) is now available for Internet Explorer and Safari.
Say, for example, you use Firefox at home, but at work you're stuck with Internet Explorer (not that there's anything wrong with that). Foxmarks will keep your bookmarks in sync between the two PCs and the two different browsers. (It also makes your bookmarks available online from any PC, smartphone, etc., as shown below.)
Just be sure to check the settings before you perform the initial synchronization, as Foxmarks gives you the option of merging or overwriting bookmarks in one direction or the other. You'll want to give some thought as to how the first sync should go.
Unfortunately, the IE and Safari versions of Foxmarks lack one key feature: password synchronization. For now that remains exclusive to Foxmarks for Firefox. Even so, this is a must-have tool for anyone who runs multiple PCs (and/or Macs) and wants to keep a consistent, automatically updated set of bookmarks on all of them.