I’ve been searching for ages for a small, trouble-free, high-quality audio recorder. I might just have found what I need — the Olympus WS-110. It’s tiny and produces incredibly crisp recordings, even without an external mike. (I bought a lapel mic to go with it, but I don’t think it’ll be necessary.) It cost £44 from Amazon and pulls apart to become a USB stick — Voila!
The one drawback is that it produces WMA files, but if you’re a Mac user then the wonderful Switch utility fixes that.