Stefan Adrian is leading a team of Open Hardware developers on a Shield called the Arduino School Board for the purpose of teaching would be makers the joy of Arduino.  The unit has a lot of hacking potential.  The board hosts:

• 1 switches
• rotary encoder
• 7 segments
• 2*16 LCD display
• nokia 1110 graphic display
• RTC
• micro SD card
• 1 Wire thermometer
• relay output
• LED PWM adjustment
• stepper motor command

Good luck Stefan!