Record Audio Externally

From MITVWiki

You'll want some kind of clapboard or method, (such as clapping your hands) to help synchronize the audio track with your video track.

[edit] Digital Voice Recorders

I don't recommend purchasing most digital voice recorders. Often they record low-quality sound, do not allow external microphones, and may be very difficult if not impossible to use the resulting audio--proprietary formats abound.

[edit] Digital Field Recorders

Marantz

Edirol

M-Audio MicroTrack

Zoom H4

Zoom H2

iRiver ifp-7XX and ifp-8XX series

[edit] Another Option

The Mini Disc isn't dead yet and can still be a useful recording tool. It offers quality audio which can be converted to editing friendly mode. The Mini Disc invented plug in power microphones (the technology the now discontinued iRiver ifp used).