I listened to over 500 totally different genres on spotify lately, it's not difficult, it just means you have to do slightly more work than blindly listening to whatever spotify shoves you? The trick is to pick a specific genre of music -- soul, rock, whatever. Use spotify's playlists to get a rough idea of the genre and then use the radio feature to suggest more. There are good genre explorers, too -- i seem to remember one posted here that introduced me to tanci/pingtan, and managed to find some example works to listen to.

Maybe you're thinking of everynoise.com -- probably one of my favorite sites on the net.

Last.fm recommendations are great for this.

Yeah, last.fm remains significantly better than Spotify for listening reccs. Better yearly stats too.