>>>
>>> I'm just curious, does anyone manufacture a turntable for O scale?  I
>>> don't recall ever seeing one.

There are at least two made in the US, which may or may not help, 
depending where you are.  Atlas and Bowser come to mind.

http://www.atlaso.com/oturntable.htm

http://www.modelrailroader.net/os_turntables.php
-- 
Graeme