Does anybody use Airtunes with something other than Itunes? Like Airfoil

Essentially, I was watching a Netflix disk of Dexter and wanted to watch the
last episode in the series...logged into netflix and watched on the Macbook.
Audio was fine, but since I have 6 pairs of speakers wired up in my ceiling
(via airtunes) I cool would it be to send the audio out the
airport express?

Seems like a dumb thing....does nothing but iTunes broadcast to the AE?