Stephen, masquerading as Sparky, raises one of my favourite subjects: the geographically-correct tube map. Coincidentally, so does Kottke, providing a link to an image of the London Underground map as it really looks. The familiar Henry Beck schematic doesn't merely straighten the lines, it also enlarges the busy centre, making the area within the Circle Line seem far bigger than it is.
I've laid the geographically-correct map over a road map of London. I'm not sure I've lined it up 100% correctly, but it's near enough. If you've got Photoshop, you might want to download this .psd file so you can move it around and adjust the opacity of the layers yourself.