I picked up the Tokina 11-16 a few months ago for my 450d. It's a good lens. Have a look at the Sigma F1.4 50mm as well as the Canon. iIt's is a sharp lens. I recently upgraded to a Canon 7d. Here are some example shots with both lenses.
http://www.flickr.com/photos/7703127...in/photostream
http://www.flickr.com/photos/7703127...in/photostream
http://www.flickr.com/photos/7703127...in/photostream