More than just pictures of electric Brill, Flyer and Pullman buses, trolleybuses.net has some great old street-level shots of many cities in North America.
Seattle is only one of five cities in the United States with a trackless electric trolley bus system. King County Metro operates 159 trolley buses on 14 routes that ply over 70 miles of trolley wire, and travel 2,906,297 miles annually. Last year, Metro found that operating new electric trolleys offered a superior financial scenario to new diesel buses. This is even before considering how much better a trolley performs on Seattle's steep hills, or how much less pollution it creates, being supplied by hydroelectric power. If you want to know a little more about how the system works, see some of the photos posted by a King County bus operator known as VeloBusDriver. Some of these photo sets explain the controls of an ETB, the innards of an ETB—so much cleaner than a diesel but so much more dangerous to poke around in—and aspects of how the trolley wire itself works, including the "special work" necessary for tasks such switching routes or traversing a drawbridge.
Intrigued by the trolley problem? Here is a link to the full text of Michael Moorcock's 1971 SF novel Breakfast in the Ruins. Moral conundrums at the end of every chapter for you. [more inside]
Trolley-spotting : Dedicated to developing a system of classification that allows stray shopping carts to be identified based on the situations in which they are found.