You can use this word for anything, it can mean yes or no or just an answer because you cannot be bothered making up anytbing more elaborate. It can piss people off, it can amke them happy all in all it seems to be a pretty great word.
Q: Are you horny?
A: Maybe (Yes)
Q: Can I get that nice new 500 dollar bike for my birthday?
A: Maybe (No)
Q: How much wood could a woodchuck chuck if a woodchuck could chuck wood?
A: Maybe (Nonsense)
The people who reside in the country Canada, who are disliked by most Americans because they know which wars to fight, and don't kill each other as frequently. It is commonly known that they use the word eh alot. Whether or not this is true, or if people are just ignorant (I favour the latter) they are a happy, content people, who are associated with the French because that's who colonized them. Why aren't Americans like that with England? Oh wait, you declared "Independence".
American: Check out those pussy Canadians...
Canadian: Am I pussy because we don't go and fight wars over some oil, and hold a pre-emptive strike? Or because we are half french? Shut up eh?