Attacking RSA with acoustic analysis. This is pretty damn awesome.
A couple of ingenious Israelis have found a way to extract keys - under certain conditions - based on acoustic analysis. It's somewhat reliable and it's fast.
This article here explains how it works. There's a pdf with more insight into the attack on the page.
Now one could argue that this attack requires quite a lot of known-knowns and some preconditions you probably won't find in many real-life situations in that combination. But with some preparations and knowledge on the target you could get to know many of them making this attack very well feasible in some situations.
Worst case: With a smartphone. Although better equipment is significantly more reliable.
Even though this is far from the attack it's a great demonstration how dangerous side-channel attacks can be if the attacker takes the creative road. And this specific attack is creative as they can possibly come.