So this is an accurate (in terms of coordinates) map of London, generated from OpenStreetMap data:
You can pan around quite a bit and use the scroll wheel to zoom. To achieve this, I created the following geographic stylesheet:
The map is built on Cartagen, a mapping framework for viewing and geographic data in a dynamic, personally relevant way. Cartagen uses the GSS (Geo Style Sheet) format, which allows users to design maps with CSS-like styles. Learn more at Cartagen.org and the Cartagen wiki, or download the source at Google Code.
Go to Cartagen.org to view anywhere in the world through this stylesheet.
Quick update: some users (read: most) are having trouble zooming in and out! This is because of a known last-minute bug in the 0.6 release of Cartagen, and only affects maps embedded in other pages. It does not affect cartagen.org. For a quick fix, to zoom you can also hold down the ‘z’ key and drag up and down on the map.
Followup update: zooming with the scroll wheel should work now. Thanks for your patience!