This gallery of custom bikes has all kinds of wheels (probably 200 of 'em), from lowriders to recumbents to customized Monarch cruisers, but the wooden ones most caught my eye:
Igor Ravbar: "Woo" Woodbike
Peter Dahlberg's Wooden Bike
Bernd Vonau's Wood'Bent recumbent
Earlier: The fake Venom line of Specialized bikes, chainless bikes, and Bikes Against Bush.