http://www.guardian.co.uk/news/datablog+uk/ukcrime - A great source of data on all sorts, not only crime
http://www.murdermap.co.uk/ - slightly morbid but a good example of google map overlay in London
http://www.trulia.com/real_estate/New_York-New_York/ - if you click "crime" it shows a great shaded map of violent crime in relation to house prices
http://66.93.183.118:8080/isee/s1?id=50&cord=?323,221 - great mapping service that offers a route of least surveilance through New York. "i-see" makes the point that CCTV cameras are very invasive and offers a solution to this loss of your privacy.
http://www.wired.com/politics/security/news/2001/11/48664?currentPage=all# - an article about "i-see" on the Wired website.
