Eons ago I used to record conversations on my third generation iPod (not to be confused with iPhone 3G. I can't recall if I was able to transfer the audio files to the desktop.
It worked quite well -- until Apple obsoleted the hardware connection!
It finally occurred to me that I could do that again. The Monster adapter I bought for my BOSE headphones works just fine as a standalone microphone - I just have to unplug it if I want to hear playback without headphones. (I wouldn't mind finding a direct cable connector for analog to analog transfer though. I don't need stereo recording ... yet ....)
Plum Record will record files that can be transferred to the OS X desktop and translated there. Audio Recorder transfers by email but uses native iPhone audio formats (.caf, uncompressed). (Yes, we all want access to that damned USB cable.)
The Audio Recorder FAQ says the iPhone will work with a standard mini-jack mike.
I purchased Voice Recorder a while back but took it off my phone. I'll have to see if they offer any audio-transfer options.