Making text difficult for OCR?

I have a question for you c'punks. If you wanted to generate some bitmaps of text which would be difficult or impossible to OCR, but not too difficult for humans to read, how would you do that? Basically, I want to create GIFs of text which can't be OCRed in a reliable way. I've thought about some things: I can put in noise pixels, I can blur the text, I can rotate, shear, and otherwise distort it. Anything else I should do? Will these tricks work? Thanks