Probably like everyone else reading this, I take pictures of buses, bikes, and trains wherever I go. I have created a searchable flickr photostream with a creative commons license (Attribution, Noncommercial, Share Alike). Please let me know if you use one somewhere.
I used the tags bike, ped, train, bus, car, boat for modes and sign for interesting signs, share for bike and carsharing, station for bus and train stations, and fail for infrastructure failures. And for some reason I also have a collection of photos of recycling bins around the world. Oh, and artsy for fun photos like this.