Beenmapped.com, which extends the notion of the bookmark to include physical locations, as of today also provides a link to a KML file for each bookmark, ready for opening that same spot in Google Earth.

(Safari for the Mac misses crucial bits of the site, as it has poor support for XSLT, apparently, but it works fine in Firefox.)

On my wishlist: the ability to keep and organize lists of my own location bookmarks, like I can with URLs in del.icio.us, instead of still needing to add them to my browser’s actual bookmarks. But otherwise this site is coming along very nicely.