The UK's Office of National Statistics has used Google Maps to show the average household income estimates for different areas in England and Wales.
You can select the income measure you want to view on the map via a drop-down menu. By clicking on the map you can then view the average household income estimate at that location. You can also search the map by an address or a postcode.
The map seems to show that the nearer you live to London the more your average income is likely to be. There are a few pockets of high earning areas outside the capital but it would be interesting to compare the data on this map to a map of commuting times into London.
ONS - Income by Location