Have you seen the successor to the Overhead Projector? It's called the Visualiser, and it is basically a digital camera in a goose-neck mount which allows you to project an image from on your desktop (that's your real desktop, not your Computer Screen).

You can place a sheet of paper under the head of the Visualiser, and write notes on the paper while the whole thing is projected onto your screen for the class to see. I think it may be less useful for projecting text, but ideal for:

• Demonstrating techniques in Textiles, Cooking and Technology
• Showing small objects (such as Religious or Historical Artefacts) to a class.
• Demonstrating note taking or annotating a book.

The cheapest are around £250. The base on this model includes zoom controls, and it connects to a computer to allow video and stills capture (though it has a small memory of its own, so should work without a PC).

In the spirit of the classic Dewar bodge, I've got similar results from a high-end webcam, costing £60. Get one with a megapixel resolution and decent optics, and you're away!You could always gaffer-tape the webcam to an Anglepoise!

This is the webcam I used - the software includes special settings to correct for low light, and the autofocus keeps even text pin-sharp. The clamp on the back of the camera allows you to fix it onto something (like an Anglepoise...).