The Laser Pen Method
What you need: Wacom Inkling, $200
Risk level: High
The Wacom Inkling is a device that allows you to transmit your pen strokes to your computer. Many will use it to transfer their analog drawings into the digital world, but you can use it to bring your answers to your friends after you take a test. The only hinderance is the receiver that needs to be clipped onto your paper. It may be a tad difficult to explain that one to a professor.