Wow. Marvel just released the first 11 minutes of Captain America 2: Winter Soldier—which will premiere on April 4. Lots of action happens in those minutes and, funnily enough, most of it is Scarlett Johansson kicking some serious ass in her tight Black Widow suit.
At the beginning, Cap meets Sam Wilson for the first time—who later becomes his best buddy, The Falcon. Scarlett Johansson appears right after. The two of them go on to take down 25 pirates—top level mercenaries, not your regular Captain Phillips variety—at a mobile satellite launch platform. And when I say "they" I actually mean "her," because she gets the best moves, including her famous 30,000-volt static electricity bite.
Apparently this wasn't released by Marvel, so they took it down.