Montreal has a fantastic public bike system called Bixi (bike-taxi), in which you can swipe a credit card and take a bike for free for up to 30 minutes. Longer rides start at $1.50/hour and are very reasonable thereafter. You can return to the bike to any of the numerous docking stands around town, making them perfect for short one-way commutes. An iPhone app will tell you the closest available bike and the closest open dock for returns. The stands are everywhere.