Comment: LiveScribe Echo (Score 3, Insightful) 425
This doesn't meet the ground rules you laid out, but you could consider taking notes on paper and then getting electronic copies of them.
I'm thinking of the Livescribe products. It's a smart pen/dot paper combination. The big additional win from the Echo or Pulse smartpen is that it will record audio while notetaking. There is an add-on app for the pen that lets you use it as a stylus for your mouse cursor on the laptop (the pen must be tethered to the laptop with a usb cable). I've never used that aspect of the pen.
The recorded audio can be cued up after class by just pointed to the note you wrote at the same time, as well as by more normal play/pause/scrub controls.
Also, the handwritten text can be searched in the base desktop application. There is an additional software that will convert the handwritten image to fully editable text - but again, I haven't bought it or used it.
You can also send complete audio/image combinations to an online account and sync them with your iPad/iPhone, so you don't need to carry around all your notebooks just to read them, though you will need them if you'd like to take new notes (assuming you keep one notebook per class, as intended)
To be honest, I bought this long after school, because I thought it was so damn cool. I haven't had much call to use it, so I can't really be for or against it. Anyone else use it in an actual class?