geotagthings - Anything with a URL can be given a latitude/longitude by simply clicking a bookmarklet, picking the spot it should be assigned using a map interface, adding a little note and that's that.
karlUshi: GOOD: easy to tag things on the Web, BAD: Yet Another I get your private data, private patterns for free (you need an account)
bblfish: looking for feedback here or on the Atom OWL group