The Sydney Morning Herald published a user’s very favorable experience with Dragon NaturallySpeaking Mobile edition which allows you to dictate into a recorder while away from the computer, then upload your work into the computer, either as text or into a wav file.
The author notes that the system only works with “digital recorders that transfer the voice at a frequency of 11.4 MegaHertz.” He used and found acceptable the Sony ICD-MS515.
I admit, I hadn’t really thought about trying the Dragon mobile stuff, assuming it wouldn’t work well enough to be worth it. This article has changed my outlook, and I may consider it at some point in the future.