This basically replaces Dribbble searches for me. We already create moodboards for clients, and it's a pain to source all the design inspiration. This just centralizes it all to one site and even lets me save stuff to find later.
A common issue I'd have in our creative process is trying to show clients how a design, function, or animation works. It's tough to convey that with just words. However, now with such a large library of content to pick from it's easier than ever to find the perfect photo/video to demonstrate your idea.
Mobile Patterns is the only big inspiration tool left and by adding gifs, they brought a whole new level to whats possible.
The buffer bar masked as a Play/Pause button - sneaky!