Whilst getting a lift home from charliemouse he gave me a demonstration of his in-car navigation system. I must admit I'm hooked on the idea of getting such a device for my bike. It would greatly decrease the amount of time I spend getting lost, or pouring over streetmaps.
The (obvious) downside to this dream, is that such beasts cost at least £180 and ideally I'd rather have a look at them in person rather than ordering them blindly online. I think a shopping trip to London is sounding more and more like a Good Idea(tm).