Frank Carver's Punch Barrel

This looks like a neat idea – a pen which records both what it writes and what it hears. It’s aimed at people taking lecture notes, but would likely be just as suitable for any other annotated-audio situation such as meeting minutes or the record and replay of spoken games.

Of particular interest is the bit where it notes:

Livescribe plans to maintain a clearinghouse online where users can download new applications, some created by the company and others by users. (Anyone who can program in Java can write software for the pen.)

Technology Review: Taking Apart the Livescribe Pulse