I know this is a strange request, but I currently creating an estate agent
type site and I noticed on somebody else's (big company - not interested in
little old me!!) that they give the user the option to see property results
that are 2, 5, 10 miles, etc away from the location that I can pick.
I think this is a really clever feature, but have a sneaking suspicion that
this kind of effect could be re-created using some kind of internal grid
reference proc rather than having to buy a £30,000 piece of post coding