iOS with OS X: You listen to music on your Mac, you listen to music on your iPhone, but transitioning between the two really kills your groove. Seamless fades music out on one device and in on the other with one tap.
Seamless gives you exactly what it says on the box—a seamless transition between iTunes on your Mac and the music player on your iPhone, iPod touch, or iPad. Just connect them to the same Wi-Fi network, hit the "Transition Music from Mac" button on the Seamless iPhone app, and keep the groove alive. It's dead simple. Check out the video to see it in action.
Seamless is a free download on the Mac side and $1.19 in the iPhone app store.
Seamless iOS Client [iTunes App Store]
Seamless Mac Client [Mac App Store]