Just a brief note about Music Publisher's. (This was taken from an email)
As far as selling songs go, what you will be looking for is a music publisher. The songs need to be registered with Socan. www.socan.ca Generally what a music publisher does is catalog songs by artists, and then when a artist (who doesn't write their own stuff) or a producer/music label is looking for songs, the publisher will then send out a specific package of songs for the person to view. In turn what generally happens when an artist is interested, they will record the song and pay the mechanical royalty to the writer and the publisher. On occasion a artist will buy the song outright, although I am not to sure how often that happens.
At our record label, we have a music publishing company which is basically used as a vehicle to copywrite our songs, and not so much for selling other peoples music.
I am sure there are a bunch of independent music publishers out there, you will just have to check around and do some research to find a good fit for you. They may need versions of your song sans vocals, plus typed out lyric sheets. Check out the association of independent music publishers