15 DIY bikes that come with instructions but no manual. Unless the manual is labor, then yes it is lots of manual labor. All bikes are found on Instructables
Pencil Bike : Who doesn't look at a pencil and wish they could ride it.
Office Chair Bike - When work and commute meet.
Wooden Bike - Greenest bike out there is by far the Wooden Bike.
Recumbent from a Kid Bike - Don't feel weird enough in your recumbent bike? This will fix this right away. The mini recumbent can make you look more goofy or immediately make it harder for your kids to make friends.