A free trial of WireTap Anywhere can be downloaded here:
Best of all, mix any combination of applications and input devices into a single, logical device. Simply select the software or hardware inputs you want, and WireTap Anywhere will handle the rest. WireTap Anywhere: Tap it anywhere.
WireTap Anywhere costs $129, is a Universal Binary, and requires Mac OS X 10.4.11 or later.