thenewspaper.com – This site has a slew of stuff about traffic enforcement, primarily photocop-related. Sure it’s biased, but it’s a great place to read about all of the problems (inaccuracy, bribery, etc.) in the photo enforcement industry.
National Motorists Association – I was a member when I lived in the US. They lobby for engineering-based solutions to automotive safety. They also have a lot of great advice for contesting tickets. They share my stance that drivers should fight every ticket.