I always surprised me how people constantly leave expensive possessions out on the street.
Car alarms
http://www.silentmajorityny.org/report/index.html
http://www.amasci.com/amateur/traffic/traffic1.html
http://www.sciencenews.org/sn_arc99/7_3_99/bob1.htm
http://www.nytimes.com/2003/10/22/automobiles/22MORA.html
Cars that can park themselves
Traffic waves
http://www.amasci.com/amateur/traffic/traffic1.html