The only usage of eh? that is exclusive to Canada, according to the Canadian Oxford Dictionary, is for "ascertaining the comprehension, continued interest, agreement, etc., of the person or persons addressed" as in, "It's four kilometres away, eh, so I have to go by bike." In that case, eh? is used to confirm the attention of the listener and to invite a supportive noise such as "Mm" or "Oh" or "Okay". This usage may be paraphrased as "I'm checking to see that you're[listening/following/in agreement] so I can continue." Grammatically, this usage constitutes an interjection; functionally, it is an implicit request for back-channel communication.
"Eh" can also be added to the end of a declarative sentence to turn it into a question. For example: "The weather is nice." becomes "The weather is nice, eh?" This same phrase could also be taken as "The weather is nice, don't you agree?". In this usage, it is virtually identical to the Japanese "ne?" or the Mandarin "ba". This usage differs from the French usage of "n'est-ce pas?" ("Isn't that so?") in that it does not use a (technically double or emphatic) negative.
The usage of "eh" in Canada is occasionally mocked in the United States, where some view its use - along with aboot, an approximation of a Canadian raising-affected pronunciation of about - as a stereotypical Canadianism. Such stereotypes have been reinforced in popular culture, and were famously lampooned in South Park: Bigger, Longer and Uncut. Singer Don Freed in his song "Saskatchewan" declares "What is this 'Eh?' nonsense? I wouldn't speak like that if I were paid to." There are many merchandise items on the market today that use this phrase, such as t-shirts and coffee mugs.
It is often joked about by Canadians as well, and is sometimes even a part of the national identity. For example, a Canadian national team is sometimes referred to as "the Eh? team". Likewise, at one of their concerts, a member of the Canadian Brass, referring to their arrangement of the jazz standard "Take the A Train", said that they'd considered calling it "Take the train, eh?". A classic joke illuminating this: "How did they name Canada? The letters were thrown in a bag, and the first one to be picked was 'C' eh?, then 'N' eh? and finally 'D' eh?"
In the Canadian animated faux-reality show Total Drama Island, one of the twenty-two teens on the show, Ezekiel, is a stereotypical Canadian yokel who uses the term "Eh", usually at the end of a sentence.