Shazam is amazing. I was in a very very loud school auditorium last weekend (for my kid's karate belt graduation....at least 100 kids and twice that many parents/grandparents) and it still picked out the music that was playing in the background.
How does it do that? (rhetorical question, not need for long-winded technical explanation)
I am going to try it at a hockey game next, but I use it constantly in the car to identify songs on the radio (even if I know what the song is, it saves it in the history so I can remember to get the MP3 later).