Housing

Most probably everybody by now will have found a place to stay. But even more probably the wish to move might arise for a variety of reasons:

The current place is too far from school. Yes, Toronto is big, and distances on the map do not look that huge :)
The landlord is evil. Welcome to North America, where tenants have no rights. Well, it is not that bad (see Ontario Housing Tribunal and Tenant's Rights, but from my personal experience I can tell you that most landlords seem to be bad in one way or the other.)

How to find a place

So what are your options to find a place?

Contact the UofT housing services. They have a listing of available on- and off-campus housing as well as a collection of more links to online housing listings for the GTA. But be aware that they do not monitor the advertised places - see personal anecdote
Browse the hardcopy or website of Renters News
Take a look at the ads in magazines like NOW, EYE or newspapers like Globe and Mail, National Post.
Keep your eyes open for ads posted to lamp posts around campus.

When looking for a place you should ponder the following questions

A more complete list can be found here

Yes, as a tenant you have certain rights! You can find out about them at one of the following places

The Ontario Housing Tribunal is a place where landlords and tenants can file motions to resolve issues. Their website however is really usefull even if you are not experiencing any problems. You can find there a copy of the Tenant Protection Act.
If your neighbours are too noisy you might consider taking a look at Toronto's Noise Bylaw(pdf)
Community Legal Education Group
Downtown Legal Services if things go really wrong - a free legal counselling service run by volunteers like law students at UofT.