Safarilicious

Del.icio.us is a superb service. One can upload his bookmarks, tag them, view them from anwhere (as long as "anywhere" is somehow connected to the internet), make them available to other people, or simply browse other people's bookmarks.

Safarilicious parses your Safari bookmarks and allows to export them to your del.icio.us account. And even more, it has a nifty Update Option which, if activated, only exports those bookmarks which are not on your del.icio.us account yet.