The Big Dog
This picture caught my eye while I was perusing the Makezine: The builder, Tom Wilson, explains it beautifully, as "A wonderfully impractical assemblage of bicycle, go-cart, and golf-cart pieces and parts, drainage pipe, steel tubing, and patio chairs. This four-wheel vehicle allows four passengers to travel in minor discomfort at speeds approaching a brisk walk, for relatively short distances, on completely flat terrain."
The "Big Dog" is Tom's entry in Make's Maker Faire in Detroit. What I love about the job Tom's done here is not only the end result, which looks amazing, well-done, and awesome (that's L-I-V-I-N'), he's also thoroughly documented his design and the build process on his website. He's got a great sense of humor about his contraption and his hobby. Check it: http://www.thirstybeachlandscaping.com/quadbike/page25.html