With Porthole you can stream to more than one AirPlay device and your Mac's speakers simultaneously, so you can enjoy music throughout your home.
Stream all music players with one click. Spotify, Pandora, Rdio, SoundCloud, Grooveshark, Simfy, Last.fm, websites etc. Porthole streams all you system audio, so all these apps "just work".
AirPlay for everyone. Porthole works on post 2007 Macs running Snow Leopard, Lion or Mountain Lion. Also, every AirPlay compatible speaker is supported!