Richard Akerman of Science Library Pad draws attention to a crime map (of Ottawa as it happens). If you happen to live in that fair city, you can use the map to see which streets are most popular with criminals. They don't really need to have such a map for Kingston upon Thames as there are only two sites for crime (two "nightclubs", O—— and The W—–), as well as the river itself of course which is convenient for dumping the bodies. (Three people who met premature ends have been found there in the 18 years I've lived here, according to the local paper.)
I wonder if someone could make, or has made, such a map for fictional crime?
However, as Richard points out about Ottawa's latest: "If this doesn't seem too novel, keep in mind that chicagocrime.org was one of the original crime map mashups, and it was only created in May 2005 (see In memory of chicagocrime.org )".
Petrona 
A crime map of the fictional Midsomer Norton or Colin Dexter’s Oxford colleges would have a Chicago and Baltimore police SWAT team running for cover.
In my time in New Malden we once had two unrelated murders in one weekend and the local police constable, who was a patient said he had done better than Maigret by solving both cases immediately before CID involvement by arresting the husbands of the victims.
As a fan of maps, I bought a map of some fictional Oxford crimes that was put together about twelve years ago, another of Brother Cadfael’s Shrewsbury at around the same time, and more recently a map inspired by Raymond Chandler’s books. There are a few others around, and on a humbler level, my website has a map of the locations of the Harry Devlin books with photos, while we are working on an illustrated map for the Lake Disrict mysteries.
There has been a crime map in Ottowa since June at SpotCrime.
The service is run independently without funds from the PD.
Thanks, all – I look forward to seeing that Lake District map, Martin.