"Thanks!"
"Thanks!"

"Thanks" has replaced "You're Welcome" as the response to "Thanks", "Thank you" etc.

"You're welcome" implies that I'm doing something for you out of good will. It's a bit condescending to think that I might have something that you need, that I could give you something you couldn't get for yourself.

"Thanks" acknowledges that I'm really just doing this for my own good, pleasure or gain.

**UPDATE**
This is a kind of absurd post, so I apologize. But it always seems odd to me when I get a "Thanks" in response to my "Thanks". It hits close to home when I say "Thanks" in response to "Thanks", and usually it's because I'd be embarassed to say "You're Welcome"