An interjection or prompt spoken by Canadians.

I am a Toronto born and raised Canadian. This is how eh is often used here:

Typically used to replace terms such as:

"Did you know?"
Ex:
Guy 1): "McDonalds replaced the double cheese burger with the McDouble on the value menu eh?"

Guy 2): "Really? Damn... those McBastards"

Often used to replace the word 'right?'
Ex:
Guy 1) "You're going to school tomorrow, eh?"
Guy 2) "Yeah, I try not to miss class"

Also replaces 'right' in the following sentence:
ImATwin ): Taylor Lautner is so hot!
sLaShK ) : I know, eh!

"You know what I mean?"
Ex:
Guy 1): "Im going to walmart to buy toilet paper"

Guy 2): "Get the thick stuff eh? Don't be cheap"

Guy 1): "Yes of course, no one likes that thin equate stuff"

"What do you think"
Ex:
Girl 1): I bought a new pair of TOMS. Cool eh?

Guy2): Yeah, they're pretty cool. I might buy a pair as well.

"Don't you think?"
Often used to ask for a response of agreement or disagreement, similar in meaning to "don't you think?"

Ex:
Guy1): Look at those dark clouds. It looks like there might be a storm coming eh?

Guy2): Yeah definitely, I'm gonna bring an umbrella

"What was that?" or "what?"
Ex:
Guy1): *inaudibley speaking, then guy 2 catches the end of the sentence "And thats why your so dumb"
Guy2): Eh!??