The conceptual City Rack by designers Ilya Tkach and Nikita Gutsalenko has a lock built-in so your can secure your bike — rather than having to chain it up to whatever fence or post you find. It looks like several City Racks can be placed side-by-side, and that they work with a payment system, just like a car meter (though probably not with a time limit). The ring-shaped design of the City Rack's lock allows you to shore up your bike from many different angles, so you can snag the frame and whichever tire you like.
Still, posts and fences have their advantages. For one, they're free. Plus, you can also use the lock you feel comfortable with. But let's say you lost your lock or left it at home, then maybe a post in the city you can depend on would be a peace of mind. Check out the gallery below for more of the City Rack.