One of the things that hasn't been mentioned so far, for Canada and I suppose Britain, is that it is possible to have what is termed an minority government. If one party usually does not get quite enough seats to hold a majority in parliament during votes in the House (form a government), they may form a coalition with another elected party (this has happened a number of times in Canadian politics).

This is called a minority government. As long as the government (the one with the most seats) puts forward legislation that the supporting party agrees with, they stay in power or have the "confidence of the House". In this way, the party with whom they have formed the coalition, has considerable power and in the past, some good social legislation has been passed in this manner and (seems like a good form of democracy in action).

This works as long as the coalition holds and if members of parliament wish not to support legislation put forward by the government, they can bring the governing party down (a vote of non-confidence where the government cannot get 51% of the votes in the House) and a new election would have to be called. (I think this is basically correct but I'm not an expert on parliamentary process).

Sort of like Nader agreeing to support Gore as long as Gore tows the line. (well not really)