This morning I've been working on producing a London Crime Map. This is a very early sneak preview. The map is built using Google's Spreadsheet Map Wizard and Yahoo's UI Library: DataTable.
At some point I hope to hack the html produced by the Google spreadsheet wizard so that I can change the tags on the map to clickable polygon areas. The idea is that instead of clicking on the tags, you should be able to click on any area of London and the relevant data for that area will appear in an info window.
My thanks to the Mapperz blog who pointed me towards the Met Office crime statistics.
Here are some US Crime Maps that I like:
Houston Crime Map
LA Times Homicide Map
Google Maps Mania also has a long list of other crime maps (in the right hand column)