ModuleRecords has a nice overview/review of portable flash audio recorders for professional use. While you can use your iPod or other flash MP3 player for recording interviews, you might want something with better audio fidelity if you're doing video work or recording concerts. I've been looking for a good device that I can use with external mikes and later sync up to my video tracks. The best devices let you use balanced mikes (less noise on extended cable runs) and mikes with phantom power (higher sensitivity mikes).
The M-Audio Microtrack seemed to be the ticket, but the review has me thinking about the Zoom PS-04 or Edirol R-1. I think I need to do more research.
some of the items on the list may soon be obsolete. for instance..see recent news on flash memory:
http://www.technewsworld.com/story/46071.html
and
http://www.engadget.com/entry/1234000827044261/
I agree that 1" or 2.5" HD based devices are most probably not cost-effective. Flash is getting so cheap that it makes sense to just use CF or SD cards and later dump to a larger HD or to DVD-R later on.
I just the M-Audio Microtrack 24/96 at my local Sam Ash. Looks like a nice unit, very small. I think it's overpriced at $400, maybe $250 is closer to what it should be worth. The definite downer for me is that it uses a proprietary Lithium-Ion battery. If you're in the field and you run out of batteries, then you're screwed unless you can recharge it (AC or USB). I'd prefer something that I can feed NiMH AA batteries into in a pinch. :-(
Replacing the LithiumIon will cost $75 + shipping, via Maudio.