Windows/Mac: Airfoil is a killer way to send your computer's audio over to AirPlay devices. Now, it does a heck of a lot more. The new version of Airfoil introduces the ability to stream application-specific audio from your computer over to Bluetooth speakers or headphones. It also allows you to create speaker groups, which essentially lets you to divide up all the various speakers in your house into different zones. With the new group feature also comes stuff like custom equaliser presets, the ability to hide speakers and the ability to adjust the sync settings. As with most of the developer's software, you can check out a trial of this new version for free, though the audio quality drops after 10 minutes. Otherwise, it's $US29 ($41) for a licence or $US15 ($21) if you have the previous version.
Airfoil 5 (Trial/$US29 [$41]/$US15 [$21])