There is also friend's playlists, which I find very useful to discover stuff.

Amounts to browsing random peoples' music. Compared to MOG's discovery features, MOG's is much better. You might get lucky if a friend just happens to find lots of new music you like though.

You can add Spotify-users to your friends list too, you don't need to be Facebook friends.

To add me, go to spotify:user:parbo or http://open.spotify.com/user/parbo and click the "Add Pär" button.