The Livescribe range of pens can record what you write and the audio at the same time.
The smartpen is a ballpoint pen with an embedded computer and digital audio recorder. When used with special paper, it captures what you write. The smartpen also captures audio at the same time and synchronises with your notes. The allows you to replay portions of a recording by tapping on the notes you were writing at the same time the recording was made. You can also control the playback, such as the speed or the position and do other nifty things.
The smartpen enables your notes to play back to you exactly what was said at the time of writing. To see this in action, watch the following video:
UCL is not affiliated with the Livescribe, we just like them.
Save money and pick one up in places like eBay- they go for about £100