Just listed out my Canon 85mm F/1.2L in the classifieds http://bit.ly/e608Tp. There she is seen on the Panasonic GH2 (above). Sad to see her go, I thought of her as a nice collectors piece, but she hasn't seen much use lately. If you're working on MFT (micro four thirds) like Panasonic AF100 or Sony cameras like the new FS100 with a shallow sensor-to-flange ratio you might get the best use out of these old lenses.
Now this FD 85mm F/1.2L is a bit of an oddity and fetches for a higher price, but for other great inexpensive Manual Focus lenses that can be had for less than $30 dollars, check out the link below. Just make sure you get the right adapter for the right type of lens you're looking at. These days you can practically find an adapter to mount just about any brand lens to any type of camera (or course results will vary).
Canon Manual Focus Lenses