here's something i've been looking for for a while now. with SyncIt, you can centralize your bookmarks, synchronize them automatically each time you edit them, and best of all, it doesn't interfere with your normal browsing activities. they have a client for Windows, and a pre-release version of the client for Macintosh.

**update 12/17/2004** SyncIt is no more. Bookmark sync client and server software have been released as open source and are currently stagnating at the bookmarksync project on sourceforge