you can buy tiny FM radios built into headphone cables, designed to add a radio to a mobile phone. these have been popular with zaurus users for the same reason they could be popular with n770 or n810 owners.

http://www.t2retail.co.uk/productDet...roduct=1200932

in fact, if you could get a combined bluetooth headset and fm radio?
http://www.mobilefun.co.uk/product/13938.htm
http://www.pocket-lint.co.uk/news/ne...fm-radio.phtml