They say you can't use FD lenses on EF bodies, so I'm making one work. I took the EF-S mount from my 18-55 and converted it to EF by hacking it up. I then took off the FD mount on my FD 28mm f/2.8 and I now just have to distance the mount from the body a tiny bit and the initial, duct taped prototype that only shoots wide open will be complete.
This hack job makes an FD 28mm f/2.8 mount on an EOS body and retains focusing to infinity (past infinity until the mount is distanced from the barrel) without a corrective optic. edit: I've been using the lens now for just a little bit. The bokeh is soft, creamy, and all around wonderful.