Thought I'd chirp in with a little tidbit.

For those in Ontario, Canada, the Residential Tenancies Act specifically states that any provision in a residential lease which prohibits pets is void.

Of course, you still have to look at the applicable bylaws (of your municipality, and even your condo). Most Ontario municipalities only prohibit venomous snakes and non-venomous snakes over 3 metres (10 feet) at adulthood.