I have Navigon Satnav, which I mostly use when in Spain and wouldn't be without. As others have said they do make the odd mistake, my one always makes it in the same place (Granada) where it tries to send me down a dirt track but I know to avoid it. It can be used in a car, bike or walking and you can input postcodes and map references, though I haven't tried this. Thy are worth the money.
