The crime mapping website SpotCrime has created animated timelines of shootings during 2008. Here are videos of the Baltimore and London maps:
Video Link (watch in high definition)
SpotCrime Timeline of London Shootings from Keir Clarke on Vimeo.
To view timelines for other cities just change the name at the end of the url. For example here is the url for the New York 2008 shootings map:
SpotCrime now provides crime maps for over 200 cities.