Ask YC: Hacking my TomTom to play video,mp3s etc

This is kind of random, and doesn't have anything to do with a startup or anything, but i'm thinking of doing the above and posting the results (somewhere).

so, who here has hacked their own gadgets,iphones,xbox etc? Any tips, suggestions? Bonus points for cool tips on the linux kernal (which tomtom is based on)