Here, try this:
http://research.lunenfeld.ca /rtc/?...r%20Studen ts
It's where I worked for a co-op term. All the PI's there have grant $$ (super important) so they can usually afford 1-2 summer undergrads. If you have an NSERC or USRA, you have a better chance of getting in (anywhere).
In general, you should look at a PI/supervisor's lab website and their most recent publications - find experience and bench work you've done that is similar to theirs. Read their manuscripts and see if that's what you'd like to work on. Contact them
directly. The professors in the Biology department generally have less money (basically none of them wanted to hire co-op students but were all taking on thesis students, who work for free). You could try looking into the Biochemistry department.