http://www.livescribe.com/
This takes coordinate points on the paper as you are writing and recording the lecture.
When you are studying later, you can touch the pen to the part of notes you don't understand and listen to what you were writing as they were saying it.... The pen can down load the stored notes, and recordings and then you can then post the notes online for free, and others can click on your notes for different parts of the lecture. Really, it's a godsend. Good to have at meeting, if everyones ok with being recorded.
Supposedly they have a development kit for this, and I would think the possibly apps would be unlimited, but I haven't seen much recently community wise about development on it. I totally wish they would set up a market for selling 3rd party apps.
The ink, and notebooks are pretty cheap for what your getting.
