“I use the iPod touch voice record function to record lectures. In addition to paper notes, this provides a means of revisiting lecture material for revision, especially if concentration fails during the actual lecture especially if I am very tired during a lecture.”
The iPod touch voice memos “saved in a Recordings folder on iPod in the WAV file format. If you enable iPod for disk use, you can drag voice memos from the folder to copy them.”
MacWorld has a useful article about recording voice memos on the iPod and iPhone with some notes about the different versions and the extra accessories needed for some models.