Have a look at a couple of the Morphy Richard radios he
http://www.ogormans.co.uk/windup.htm. They are wind-up and solar powered,
although not totally waterproof, they are shower and rain proof.

My mistake, it appears that only the Freeplay models are solar powered,
whilst the Morphy Richard ones are splash proof.

Cheers

Nick
http://www.ukgardening.co.uk