Federal Student Work Experience Program
This is a program that claims to place about 9,000 continuing full-time students in jobs every year. They say they receive about 50,000 applications a year, but, as the saying goes, you can't win if you don't have a ticket.
You apply by submitting your application, and then, if you're lucky, they contact you. Seems like a possibility for summer jobs.
The link for more information and to apply is: http://jobs-emplois.gc.ca/fswep-pfete/index-eng.htm#q2