What I sometimes do with my camcorder is simply place a dictation recorder in a good or convenient location and just leave it on. For instance, on travel agency bus rides, the tour guides often talk lots of BS, spiced with occasional good stories. With my camcorder, I never catch the good bits. With my dictation recorder, I always do because it is always on (or in voice-activated mode). How do I use the audio from the recorder? I use some audio-processing software to extract the good stories as convenient MP3 files. I edit the movie with Pinnacle Studio Ultimate 14 (almost any movie editor will do). I place the movie (video+camera sound) on the main editing track and the external audio file on an auxiliary audio track. When I compress the time scale enough, I can see that the sound intensity profiles of the audio tracks are similar but the external audio is offset to the camera sound. I then shift the external audio until it looks aligned with the camera audio. Then I expand the time scale and do a more precise alignment, zooming in (on the time scale) as long as it takes. The final step is turning off the camera audio track.
As Stan said, even the simplest of mics (or recorders) placed close enough to the source outdo the fanciest equipment far away.