I used a Raspberry Pi along with a PiRack, a Raspberry Pi camera module, a portion of a Pi Cobbler Kit, and a white LED to create a document camera for use in a high school classroom. Document cameras typically cost hundreds of dollars. Public school budgets are tight these days. This RPi + PiRack + RPi camera module is an affordable solution that works with existing classroom technology (the projector that is already installed). From the command line: sudo raspivid -t 0 -fps 20 -br 66 gives a nice image. At a height of around 13" above the document being examined, the document camera makes the writing on half of a letter-sized sheet of paper visible to all students in the classroom. The older ceiling-mounted projector accepts composite video input. This works fine. Better viewing results could be obtained with a modern projector that had HDMI inputs.
Adding analog and digital interface card to Pi with remote control via Internet with Java or Bluetooth for local mobile access with same controls.