We've seen an increased desire by clients to add mapping to their websites – but they usually don't ask for it that way.
Clients begin by seeking new ways to visualize their information and make it easier to sort through information. In other words, they are looking for ways to make the content more relevant to the user.
Some examples – I sat in a meeting today with an large professional association where the executive director talked about the "fire hose" of data their current site provides. It's too much; it's not relevant. His quick solution – not a better search or filters or better information architecture – is to show people and businesses near the user.
In his mind, nearer to me = more relevant to me.
A map view of search results is the ideal way to present this information rather than a filtered list. Why? Because maps offer a visualization of information that is easy to scan – and scanning is the way we all read on a screen.
Here's another example – we launched a website for Lesley University last fall. Lesley offers off-campus programs in 250 sites across the US. I knew this – but it wasn't until I saw all 250 sites plotted that I understood at glance where they offer classes.
What's essential here is that the prospective student is asking a number of questions about the degree program: cost, time commitment, value, and course material. A standard text search is good for finding courses by name, but this isn't the only important decision factor. In this case a map more quickly answers other questions – how far will I have to drive? does this fit into my life?
The Google Maps API provides a way to plot your data on the Google Maps base. Plus you can plot third-party geo-coded information – such as transit stops – to add more value to your users. In addition, your users can add data to your maps such as polygons and lines plus the supporting meta-data.