SeaMonkey 2.1 includes support for Live Bookmarks. However there is a bug whereby a live bookmark never automatically updates. This means that you have to manually reload the bookmark to get it to update. This extension works around the problem by starting the live bookmark update service. This extension is restartless, so it will start the live bookmark update service as soon as you install it.
The fix for this bug should be available in SeaMonkey 2.3.