I recently just got a new lens for my Canon T2i. It's a cheap but really good lens. It's the Chinon 55mm MC (Multi-coated) f/1.7. It's an old M42 lens for film cameras from the early 70s and earlier. The image quality is just as good, maybe even better than a lot of today's lenses, and it was relatively cheap. I got it for $70.
The only thing that I don't like about is that there is no autofocus and that it needs a special adapter ring to work with canon EOS cameras. I may upload a test video to youtube soon.