Fly Math Box
If you were one of the nice people who bought Fly off my site...do I have a useful surprise for you! The Fly Math Box contains special Fly Math paper, and a cartridge for your pen. It is rather simple but strangely useful calculator-type thing...you draw in your problem with the answer, and the program tells you if it's right or wrong, and tells you how to correct it. It's good if you have homework and need someone to check it. I'll provide the link here, here, and here.