The AA Route Planner
The first of some great Google Maps mash-ups today is this route planner from the Automobile Association in the UK which actually improves on Google's own driving directions.
Like Google's driving directions the AA route planner shows the route of your journey via a coloured polyline on the map and also provides a detailed breakdown of the journey in a sidebar.
It is in the detailed breakdown that the AA excels. First off, the AA site mirrors the colour coding of UK road signs. For example, in the screenshot above you can clearly see when you move from an A road onto a motorway and vice versa. The AA route planner also includes traffic camera warnings in its directions and tells you when you will be passing a gas station, a hotel and or even an IKEA (just in case you need some Swedish flat-pack furniture on your journey).
Like Google's own driving directions it is possible to click on any stage of the journey in the sidebar and the map will pan to that location. But even here the AA improves on Google's directions by opening an information window with a zoomed in map of that stage of the journey.