I want to do some geographical visualisations as part of a .net web app. I am quite open to non Google solutions. I'd like to show concentrations of customers. There are lots of customers so I don't want to use pins. I was thinking of colorcoded postcode areas. Can anyone suggest any legal and preferably free way of doing this. The boundaries don't need to be postcode but I think that would be the best fit.
Cheers, Chris.