Anybody good at sat nav hacks?

[orange71]

I've just bought a NavMan ICN520 and by looking around on the web I can see that you can hack it to run other versions of mapping software as well as other apps (Office/games etc). Anybody know what's the best and easiest hack? What else can I look to do?

I'm interested in running memory map for example so I can see OS maps on it (perhaps for biking?). How can I get this to work?