Can I ask if you are feeding him? If you feed him regularly, he'll probably stick around for a picture, then long enough to perhaps find his owner. Here are some websites where you could post his info.
http://www.petfinder.com/post/classifiedhop.html
[url]http://www.canadastrays.com[url]
[url]www.flealess.org[url]
You could also put up some posters and fax a copy to vet offices around town. I think it might be free to post found animals in the Ottawa Gazette.
As incredible as it seems, it's very possible no-one is looking for this sweet boy. Petfinder has listings of rescue groups in your area; maybe you could call a couple and see if they could come get him.
But please arrange to feed him if you can, starvation is a long painful process and you would be doing him a great favour. It doesn't have to be the most expensive food.