If you are into walking and are sick of paying £8.95 for an OS map for every new area you go to. It's a total free to use mapping system.
In the box top left just type in the place name (works 99% of the time).
You can zoom in and out; you can right click way points on the map and best of all save your .gpx files. Then print out the map on your PC printer. It also works out the distances for you.
Never buy an OS map again.