Yeah there do seem to be a few options around the forum. Unfortunately it is a little difficult with the FM solutions. Can't wait 'till everything's satellite but then i know nothing about it it's probably even more complex
In any case I for one will be keeping some sort of head unit. Maybe a hidden one would be worth it? Like the othhers have said it depends on your preference and how much radio you listen to.
There is a post somewhere on here about a device that has an external antena, i think the guy had to hang it out his window