Steve points out an interesting use of Firefox's new "Live Bookmark" feature. Point it at the RSS of your del.icio.us account and you've got instant synchronised bookmarks. This is a problem I've talked about before.
Only problem with this approach is you just get them in chronological order, losing all of del.icio.us's categorisation features. You can painstakingly go and add each category, but there needs to be a nicer solution.