Product Lust: AirFoil
Rogue Amoeba has software out now called AirFoil (http://rogueamoeba.com/airfoil/ ) which lets you stream ANY audio content (from Real, iTunes, Windows Media, RadioShark, your XM web player, any line-in device) through multiple AirPort Expresses…. in sync! That is insanely hard as Airport Express’ have a weird delay on connection.
This is a good alternative for a Sonos device for getting audio simultaneously to multiple rooms in a house. Here’s a good setup (borrowed from my home one).
Living Room – Airport Express with optical out to your stereo
Bedroom, dining room, office, etc. – Airport Express with a set of desktop speakers (pretty looking of course)
For use as a remote control, I have an old iBook I got on ebay that just has iTunes connecting to my G5′s library, and streaming out to our Airport Express in the living room. Have it send through AirFoil and you have a multi-room home entertainment system for pretty cheap (much cheaper than the 3000 dollar startup cost for Sonus, plus it supports FairPlay).
Given adequate airport coverage, you could have four airport express’ with speakers around your home. With USB powered speakers, you won’t even have to have a power-brick.
Bonus: Airport Expresses also passively relay your Airport signal, so you get more coverage of your home Internet connection.
I’m available for installs on weekends 