46. Bike Hikes
Location: Various (check website)
Biking isn't just a way to save the planet and keep your ticker working all in one fell swoop, it's also a great way to see the city in a new way. No stranger to loving the bi-wheeled, Chicago offers gads of specialized tours by bike, including night tours and lakefront cruises.
They offer a number of specialized, one-time tours, including one based around doughnut spots in the city. So much for keeping heart healthy.