Canada actually was a large participant in several areas of the Second World War both in the Pacific and in Europe.
Firstly the Dieppe Raid was comprised of mostly Canadians from the 2nd Division and of the 5,000 who participated only 2,000 returned home (http://www.mta.ca/library/courage/canadasroleinwwii.html). Canada also was designated to land at Juno Beach with around 14,000 Canadians taking part in the landings on D-Day. Following the landings Canada fought through France and Normandy and the 1st Canadian Army liberated Holland in May of 1945.
By the end of the war Canada had contributed over 1 million people to the effort and around 45,000 gave their lives. Canada's navy was the third largest of the Allied forces and the air force was the fourth largest (http://www.veterans.gc.ca/eng/remembrance/information-for/educators/facts-cananda-involvement-second-world-war).
Since the blood sacrifice has already been covered here are some quotes from Canada at War on the production contribution of the Canadians.
"The Canadian government took full control of the economy, and turned it into a war-winning weapon.
During the Second World War, Canadian industries manufactured war materials and other supplies for Canada, the United States, Britain, and other Allied countries. The total value of Canadian war production was almost $10 billion - approximately $100 billion in today’s dollars.
The Canadian contribution began early and made a crucial difference to the winning of the war. For a nation of 11 million people it was an incredible accomplishment."
"Britain had entered the war with 80,000 military vehicles of all types; however, 75,000 of these British vehicles were left behind in the evacuation at Dunkirk in 1940. Virtually defenceless on the ground, Britain turned to Canada - and particularly the Canadian auto industry - to replace what had been lost. Canada not only replaced these losses, it did much more."
"Of the 800,000 military vehicles of all types built in Canada, 168,000 were issued to Canadian forces. Thirty-eight percent of the total Canadian production went to the British. The remainder of the vehicles went to the other Allies. This meant that the Canadian Army ’in the field’ had a ratio of one vehicle for every three soldiers, making it the most mechanized field force in the war."
One huge role Canada played that is generally overshadowed by the Battle of Britain (not to down play the importance of the Battle of Britain) is Canada's role in the defence of Malta. (http://en.wikipedia.org/wiki/Siege_of_Malta_%28World_War_II%29) It was during the siege where the famous Canadian Pilot, George 'Buzz' Beurling, got 27 confirmed kills making him an ace (http://en.wikipedia.org/wiki/George_Beurling).
Another largely forgotten campaign were the Canadian transport squadrons who would regularly fly in supplies for allied forces operating within the area (http://www.veterans.gc.ca/eng/remembrance/history/second-world-war/historical-sheets/burma-campaign).
Not necessarily military-related but interesting and forgotten nonetheless were the Canadian firefighters who went over to England to assist during the blitz and attacks on London and the surrounding areas throughout the rest of the war http://www.firehouse651.com/posten/index.html
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Canada also provided a temporary home for the Dutch Royal Family when they were sent into exile. Princess Margriet was born in Ottawa with a special decree from the Prime Ministers office temporarily disclaiming the territory making the labour rooms not officially Canadian, thus keeping her in line for the throne. http://en.m.wikipedia.org/wiki/Juliana_of_the_Netherlands. As a thank you, the Dutch sent one hundred thousand tulip bulbs to Canada, and that is the reason for the annual "Tulip Festival" in Ottawa. http://en.m.wikipedia.org/wiki/Tulip_Festival_%28Ottawa%29
I remember hearing about how a lot of British children were sent to Canada during the Battle of Britain & the Blitz, many of which were then subsequently orphaned. Can anyone shed some more light on this?
Aside from the statistics of Canada's direct contributions, there were thousands of Canadians serving in various commonwealth forces. An example of this would be a Canadian flying with the RAF versus the RCAF.
Hyperwar has a number of good resources concerning Canada in the Second World War, if you're interested in further reading. I found The Victory Campaign a particularly useful work about Canada's involvement in Northern Europe from Normandy to V-E Day
Did no one mention the Canadians in Italy or North Africa? Google is your friend. I'd recommend montecasino or orontona for the italian campaigns. I don't know much about the africa campaign though...