Zef Hemel, car-free zones: http://www.zefhemel.nl/?p=9327
What about freedom from other things? Cities like IRC, a hundred different channels, each with their own focus, and their own acceptances.
We already have alcohol-controlled zones (anti-social-free zones?) so keep going. A politic-free zone. an electronic-free zone. an emotion-free zone. a music-free zone.
Of course, freedom from one thing implies freedom to enjoy something else. By banning cars/alcohol/politics/music/etc, what are we really designing our zones to give us?