I would pay ~1.7x the current price for a version with a microphone, even if you dropped the GPS or accel. to make room for it.
Is there any (relatively simple) way to hack a microphone in there? I'm not looking for ultra-high quality sound/bitrates. Recognizing some voice commands and recording audio notes (for those with short memories) are the use cases.
I did not find anything in my cursory Google search that implied a microphone / piezo could be rigged up with an ADC and implemented.