Google's sound search widget has been released to the Google Play Store letting you do from the home screen of your android device, what you've already been doing through apps.
Google's "Sound Search for Google Play" widget was previously only available on Android 4.2 Jelly Bean, but now it's compatible with 4.0 Ice Cream Sandwich. Thus, it has been released to the Google Play Store and is available for free in the North America region.
The Sound Search widget can be dropped onto the home screen of android devices and allow you to search for a song with the touch of a button. If a piece of music is playing around you and you don't know what it is, this is the tool for you. The widget is really very similar to apps such as Shazam and Sound Hound, with a key difference, which may indeed make it worth a download:
The Sound Search widget is integrated with Google Play, meaning that a song you hear in a coffee shop will be available for purchase in the Play Store when you get home. Unfortunately, for the time being, the widget is only available in North America