Apple’s own AirPlay technology lets you fling audio from iTunes to other devices on the same network, but it’s limited to iTunes. What about audio playing inside other apps? That’s what Airfoil is for.
So if your musical listening extends beyond iTunes, into applications like Pandora or Last.fm, or if you’re an internet radio nut like me, or just want control of any other audio input you can think of, Airfoil is the application you need.
You don’t need to have an AppleTV or Airport Express to play the audio at the other end, either. Airfoil can send audio to virtual speakers made of software, which you can install for free on any other Mac, iOS device, Windows or Linux computer you have lying around.
You can try out Airfoil for free, and if you like it a license costs $25. For music and radio lovers who listen all the time and want to listen wherever they are in the home or the workplace, it’s a steal.