In reply to Choss:
> How about a Handlebar bag?
> Carries fair bit of stuff, plus keeps map visible.
My experience with handlebar bags is that they can seriously upset the bike's handling if loaded with anything more than a snack and a lightweight fleece. Scariest moment of my cycling life was a high speed descent of a hill somewhere in Surrey when I discovered that the damn bike just would not turn in to a left hand bend. Fortunately there was nothing coming the other way, and the hedgerow on the other side was quite soft...
I've used a handlebar mounted map holder and found it vaguely useful, though you wouldn't want to be riding along staring at the map for any distance. Its main utility seemed to be that you didn't need to furtle in a bag to get the map out when you stopped to check your route.