Is that what Russians say when something's intresting?

No, Russians say this when they doubt if something is true.

Thanks, but that's not what I mean. It's hard to explain to people who don't know every day english.

to Kyle: The options I listed above are exactly what you meant, actually they are the most common ones, anyway, any others are possible in the spoken lamguage as well.

Kyle, you can say да ну or вот как in this case, if I'm not mistaken. What is the context?