favthumbs.com can show your del.icio.us Bookmarks visually in a Grid or Coverflow view. Favthumbs only needs your del.icio.us user name to import all of your bookmarks & tags.
Bookmark Previews is a firefox addon that can also show your firefox bookmarks in Grid or Coverflow view. Use the Delicious Bookmarks 2 addon to sync your firefox 3 bookmarks with your del.icio.us.