Here is an interesting — if slightly gruesome — mash-up site: MurderMap.
It combines a Google map with information from London court records to plot the location of all murders noted across the region in the records. I don’t know how far back they have got yet; probably not that far as my old haunts in Lewisham seemed suspiciously light on the number of pins in the map. I don’t think it was a particularly dangerous place to live but I am sure I recall more cases than are presently shown, even in the twelve years I lived there.
Is the site all for titillation? Not according to their about page. Instead, it is an effort aimed to promote awareness of the actual occurrence and discussion of this category of crime. Definitely worth a perusal, certainly for Londoners.