Seattle has a city tour on a crazy boat-bus called the Duck. It can go on land and sea, with a guy or gal on the microphone telling people what happened when and why our town is cool. I want that, biodiesel powered, cooler looking, with an ecological backbone. The thing would take eco-tourists to our new excellent library with its energy-efficient design, stop by the newly greenly architected local libraries with their green roofs, swing down to UW fisheries for a look at what we're doing to save the salmon, and catch a mini solar tour of homes that are off grid in the city. If this idea worked out locally, you could simply copy the thing in other cities and franchise the concept. You'd be served yummy organic fair trade shade grown coffee, and visit the roaster that made it. It would be biodiesel powered, and you could visit the local biodiesel coop that made the fuel.
Bonus tracks: The same vehicles could run on rails and take the winery tour as well, showcasing our sustainable wineries and breweries. I won't call it a "drunk bus" but someone else might...could be the tour that brings in the most cash, methinks...
Could also be adapted to be entirely off-grid and mostly human-powered. You've seen those beach cars that 8 people sit in and bike around town, if you slapped on some sails, solar panels and a small biodiesel powered outboard motor for emergencies, you'd have an even more sustainable ride for the water part of the trip.
Aqua Eco Tours.