Yes, they make digital. They work by taking the audio and storing it into the memory chips of the device. If you just wish to record notes at home you can save your money by downloading audacity and using your computer as the recorder.
Check out the little Creative MP3 players, everything from the 256MB size up has a built in mic for voice recording. My 8 year old just saved up his allowance and bought the 256 MB size for himself and thinks thaat feature is a hoot. Plus they are as cheap as a small tape version $34.87 at Wally World last week. I think they are called MuVo players.
Update, the little bugger just walked by with his player and I checked how long it would record voice. Can you belive just over 16 HOURS. Granted it isn't CD quality, but better that those tape ones used to be (I had 3 or 4 while in college). Hope this helps your search.
Thanks for the info guys. Let me be a little more specific. Going back to grad school and I always hated when I had to flip the tape over in the middle of a lecture. I was hopeing there was something out now that could record 5-6 hours (quality) at a time?