Several cities in Spain now have a public bike system. You pay 20 euros a year and you can use any of the bikes for half an hour for free. You pay half a euro for every half an hour after that for up to two hours.
In cities like Zaragoza it is working so well that there is a waiting list to join. Cities like Barcelona have run into a few snags. Barcelona is on a hill. Turns out that people like to grab a bike to coast downtown. Nobody wants to ride back up the hill so they have to truck the bikes back up hill!
I saw lots of people riding bikes in both Zaragoza and Barcelona.