Ok... I guess it's my turn. I have to say that the terms I'm about to list are from the areas I have lived in or where my family or wife's family originated (mostly Eastern New Brunswick, Quebec North Shore around Sept-Iles, Central Ontario as in Lindsay/Peterborough area, etc...). Keep in mind also that these will no doubt be rather easy to get for most of you, seeing as they are probably somewhere right up the middle between american english and british english... There are some one-word terms, but a lot of them are more expressions or sayings...
One I heard quite a bit growing up was "Madder than a wet hen", usually refering to my Great-Gran...
A bundle of dried fish (usually salted cod) was referred to a faggot.
Someone taking an awful scolding would be taking a carding, a raking, or a cacking...
On a good party week-end, you might go through a couple of 2-4s, maybe more...
If you live in the sticks, you may have to resign yourself to watching Farmer Vision (the basic 2-3 tv channels, one being the CBC, the very, VERY poor distant cousin of the Beeb...)
Our dollar coin is refered to as a "Loonie", due to the picture of a Loon adorning it's one side; when the $2 coin was introduced, with a bear on the front, it was christened the Toonie! Original, eh? ;D
Oh, and did I mention that, apparently, we end all our sentences with "Eh?", eh?

In honour of my favourite aunt, who hails from Newfoundland, I shall not relate to you the shortest conversation know to the English language. I shall preface this by introducing 2 Newfoundland slang terms: Arn, and Narn. The former can mean "either one" or "anything", the latter means "neither" or "nothing." The word "by", is the translitteration of the word "boy", which comes out like "by" and is used fairly commonly in speech.
Fisherman 1: Arn, By? (Meaning "did you catch anything today?)
Fisherman2: Narn! (Meaning "No, I dod not catch anything today.")
Interestingly, a lot of the expressions from the UK are heard fairly commonly in Canada, especially in rural areas, where the cosmopolitan influence of the big cities hasn't been felt quite so much... Lavs, biccies, cuppa, ken, chuffed, cannae, dinnae, are all commonly heard.
That's about my contribution for the time being... I can only imagine how amusing it would be to have a wizarding school in some remote corner of Canada... Wasn't there a quidditch team from Moose Jaw in "Quidditch Through the Ages" ? Having been to Moose Jaw, I can tell you it certainly is remote enough!
Cheers!