The worst is when you manage to find a frequency that isn't being used so you get a nice sound coming through the cars speakers and then you actually drive somewhere.

It then wrong especially when you are not staying locally because as you drive radio stations decide to use YOUR frequency.

I have not tried this on the n900 but I imagine if you lived in the Antarctic or somewhere else as densely populated it work quite well. However, if you live in a large city with lots of commercial and pirate radio stations then save yourself the hassle and just don't bother.