I've been playing a lot lately with Google maps working on a little side project that my wife got me interested in. They've done some really interesting things recently that I'll be looking to leverage in the new application I'm working on (not work related).
First, there is the new My Maps feature which has been added to $g(Google Maps) where you can create customized maps and share/publish them via the Google Maps Index. Next, they added the ability to make $g(Google Spreadsheet) data which is one of the things I'd been working on myself so I may have to re-think things a bit.
If you're interested in map at all you might want to subscribe to the Google Maps blog feed