TuneIn Radio is one of the most popular streaming music services on any mobile platform, but it has just gotten a new feature for Android users. From now on when you hear a track you like, tap the Google Play button at the top of the 'now playing' screen to head right to Google Play and buy it. See the before and after images below.
For those not aware, TuneIn Radio streams over 70,000 radio stations live, and it's not just music. There's general talk and sports radio, as well. The podcast directory also contains a huge number of feeds to peruse. The Google Play link will conveniently bring you to the search page for the song, not just the music store section of Play. Songs you've added to favorites can also be bought through Google Play later.
The free TuneIn Radio app does all the basic stuff, but there are ads that slide up from the bottom. TuneIn Radio Pro ($5) loses the ads and includes the ability to record radio streams, though many of them are of mediocre quality.