Decent Mapping, Almost
Google Maps may hold sway, and Bing Maps may be doing their best, but if you’re old-school and actually want to be able to read the lie of the land, OS OpenSpace is ideal for embedding in your site.
Contours and details are very welcome, and the markers even have a nice sharp point. I presume that the Pro version, which OS charge for, has many extra features.
These maps still suffer from the most major failing of some online maps—the lack of a scale. Perhaps this is explains why the Planning Inspectorate of Wales struggle with maps. Come on Ordnance Survey, rich detail is great but it’s not much use without the ability to measure distance.