After many attempts, Elon Musk's SpaceX has landed a Falcon 9 booster rocket on a freaking drone ship in the Atlantic Ocean. It came down from space and just stood there. Just watch this madness:
Why is this cool? Well, it's so insanely hard that it should give you all kinds of humans-are-amazing and we-live-in-the-future vibes, which are nice to have sometimes.
For a ton more specific and less touchy-feely details about why this is cool and important, though, I can't recommend Tim Urban's epic How and Why SpaceX Will Colonize Mars post on Wait But Why highly enough.