It used to be that, in astronomy, a small team of people could look at photos of a few thousand galaxies and classify and catalog them relatively easily. But now, with a new generation of robotic telescopes scanning the skies constantly and producing millions of images, that's become next to impossible.
My personal fascination with the power of the crowd has been growing: Exactly what can a 'crowd' accomplish? We know crowds can raise billions of dollars, create Wikipedia, and even design and build small autonomous drones. But how about something large and complex like designing a new car, and maybe someday even a spaceship?