I was caught out in a meeting and discovered my Nokia phone had a voice recorder feature. (Can't remember the model - I have a different one now.) The quality was surprisingly good. The only problem was the lack of memory - probably because it was pretty full of photos at the time - which meant I only got 30mins or so.

If you have a phone, you might want to check whether its up to the job. Could have to save carrying something else around.

Unobtrusive too. People are used to seeing phones on desks.