Even if it has a clunky interface, I enjoy Pogoplug for this reason exactly. It is local storage but it acts as your own personal cloud.
If you look at the way they developed this list, it is closer to how Google ranks their searches. The metrics are scored on how many other pages link to the sites. For example, reddit and slashdot aren't high on the list because they link to other sites but very few link back. Creative Commons is in the top ten because everyone links there. It also explains why Myspace is so darn high.