In our college programs at Ohio University and U. of Pittsburgh, we invariably always meet up with the "Critical Mass" people. What is "Critical Mass"? It's not as dire as it sounds. Instead, it's the bi-weekly/monthly get-together of local biking enthusiasts to politely "take back the streets" from the gas-guzzling populace.
And as we can read from this interesting article, choosing to get about your life on a bicycle sends out many positive, practical vibes in today's increasingly unsustainable world.