This looks worth doing. Basically you can use the source to push onto TI’s Stellaris system (costs $5) and you have a mini 3.3 or 5 volt logic analyzer. The author is using logicsniffer (opensource) for the GUI and handling the data from the board. Definitely have to bookmark this on. BTW this is much cheaper than buying a solution from seeedstudio which has hardware board for $50 and the probes for another $6…oh and shipping.
http://www.fischl.de/arm/sllogiclogger_logic_analyser_for_stellaris_launchpad/