I'm not sure if you are interested in checking out the Greek Life at U of Toronto, but here is a good start....
http://www.canadiangreeks.com/directory/uoft.html
Being American, you probably like baseball? If so, you may be able to see a Toronto Blue Jays game at the SkyDome. Don't forget that we have basketball (The Raptors) and also hockey (Leafs, which you will likely NOT be able to get tix for given that it is playoffs time now)
Another activity which you may enjoy is to catch the ferry from Queens Quay (Quay is pronounced "key") and go to the Toronto Islands. Centre Island is quite beautiful and nice to visit. I'm not sure if you are interested in museums, but I have hear that the ROM (Royal Ontario Museum) is good, and also the Art Gallery of Ontario (I've never been myself).
At the Paramount Theatre (John Street near Queen Street, around the corner from City TV -which is where we have Much Music, which is Canada's idea of MTV), at the Paramount is an IMAX theatre and I saw a really cool 3D movie called "Haunted Castle". It may still be playing when you get here.
Be sure to take the Queen Street Streetcar and go to the neighbourhood called "The Beaches". It is quite pretty and lovely.
If you like interesting foods and cheeses, go to Kensington Market (College Street, just west of Spadina)....they have fruits, veggies and cheeses like you would not believe. Also there is St. Lawrence Market which is near Front Street (Walking distance from Union Station).
If time permits, I would also say it is worthwhile to go with Gray Line or Greyhound and take a daytrip to Niagara Falls.
Hope that this helps!
