Would like to find a position that I can apply my knowledge/skills to (i.e. not a grocery store position) this summer. Finishing 4th year and waiting on grad school replies in the meantime.

Where/how can I go about doing this? I have about a year of research experience in visual development lab and doing an honours thesis atm. Thanks for any help!

Ask your thesis prof for a job position?

Most hospitals with paid positions for summer students in Toronto stopped accepting applications a few weeks to a month ago. They are very competitive and fill up quickly. For anyone interested, some of these programs are held at St. Michael's Hospital, SickKids, Mount Sinai, and labs at U of T (ex. The Donnelly Center).

For something this summer, your best bet is to talk with your thesis prof (as has been recommended) or to apply for an Industrial NSERC USRA award with a project supervisor whose work you're interested in (and has NSERC grants), since the normal NSERC USRA applications were due last week. Alternatively, there's OscarPlus, but I'm not sure if positions posted there are still available.

Regarding the NSERC, I only found undergraduate and postgraduate applications. I'm not in the position to apply for either at this point :/

Perhaps try asking profs in your lab?
Hamilton Children's Hospital might be hiring, I know a few of my fellow classmates have fairly easily gotten positions there!