Motorcycle. I know a guy who bought a decent used one for 2800 bucks, gets about 35-40 depending on how hard he rides it. With diesel heading fast for $4/gallon all the time, I'm seriously thinking about one.

But I don't have a fiance to yell at me if I lay it down and leave half my hide on the asphalt. So spend some money on leathers if you get one.