One vote here for Airport Express. Much better and easier to use than the BT solution. You can get them for $69 if you look around. Get several, you can pump iTunes into all of the at once, in sync. Distributed audio the easy way. In iTunes you get a little control panel with independent volume controls for each Airport, and a master for everything. Nice. They also will drive optical/digital into a DAC if you want something more high-end down the road. Nice little WiFi extender too.
Apple TV is nice too, but more of a pain if you don't use the video feature. I've got two Airports, one Apple TV second gen. Love then all, and sometimes run them all at once!