Every songwriter knows that ideas--lyrics, melody and such--frequently come at times when you don't have a guitar, pen and paper handly, much less a multitrack recorder. But if you don't get them down, they're long gone and forgotten.
For a few years I carried a mini-cassette recorder in the car with me, because, oddly enough, I would get ideas for lines or melodies while driving. Of course I have a notebook (or notebooks), for free-writing and such. That was good for capturing ideas, but if I wanted to record a demo, I'd have to setup the microphones and my multitrack recorder.
Last December I gave myself a Christmas present: an Edirol R09 handheld digital recorder. I highly recommend it. It's easy to use, and the fidelity is great--of course, WAY better than a mini-cassette recorder or a boom box. In fact, the built-in microphones are good enough to record a concert. You can record to either .wav or directly to .mp3 files, then just transfer the files to your computer with a USB cable. I put two new songs that are in the first draft stage on my myspace site (myspace.com/rroper). I recorded them by simply setting the Edirol on the music stand next to the lyric sheet, and recording voice and guitar at the same time.
By the way, I'm not being paid to promote the Edirol R09. There are other similar products by Zoom, Tascam, Sony, etc. I can't say if those are better or worse. I suspect they're all pretty good.
Yesterday I got new cellphone, the Palm Centro. It has an application called "Voice Memo". The fidelity is crappy, but I think it will be fine for capturing lyric ideas if I don't have my Edirol with me.