I've had rotten luck with voice recorders. Quite a few micro-cassette recorders have conked out on me over the years (sometimes while conducting interviews for magazine articles). Once I used a minidisc recorder and ejected the disk without first stopping the recording and I lost everything.
When I interviewed Martha Stewart for Wired last year, I used both a tape recorder and a microphone attachment for my iPod to record our conversation. When we sat down to talk, I decided at the last second to I pull out my laptop and used the built-in mic to record the conversation.
When I got back to the hotel room and turned on my three recording devices, I learned that the tape recorder and iPod didn't record the conversation (probably my fault), but the laptop recording was OK. If I hadn't used the laptop, I would have been dead in the water. No way would Martha have granted me another interview.
Currently I'm writing a book about DIY, and I'm interviewing a bunch of alpha-DIYers. As I'll be walking around talking to people in their yards, workshops, launch-sites, compounds, and so on, using a computer to record my interviews with them is not practical. Last week I bought an Olympus WS-110 digital voice recorder. So far, it's worked beautifully. The interface was pretty easy to figure out, and the built-in USB plug is very handy. I just stick it my computer and it mounts like a disk. I copy the file (WMA format — bummer) and use ffmpegX to convert it to MP3. Then I use the excellent Listen&Type to play the audio file when I transcribe.
It uses a single AAA battery (advertised to run 21 hours per battery), and you can switch the microphone between dictation and conference mode. The 256 MB of flash memory records almost 18 hours in the high quality mode (which is what I use) and 69 hours in the lowest-quality mode. I guess you could use the thing as a jump drive, too.
I'll let you know if this thing let's me down, but so far I have a good feeling about it.
Olympus WS-110 ($(removed) at Amazon)