Shazam is an ingenious and free application that can identify the name, album, and artist of a song just by hearing it over your iPhone's microphone. That means you can hold up your iPhone to a song that's playing--on the radio, in a coffeeshop, at a party--and in a matter of seconds, Shazam can often tell you what song you're hearing, along with (if available) the album art, related YouTube videos, and iTunes purchase links. Shazam is surprisingly fast and accurate, but it works best in fairly quiet environments and/or with fairly loud music, and the closer you can get your microphone (on the bottom of your iPhone) towards the source the better. Shazam also doesn't do well with more obscure music, and it only helps with recorded music (i.e., you can't hum a few bars). Shazam keeps track of your "tags" (the songs that you've asked about) and lets you add photos and share your tags via e-mail.