Dropbox Paper
For the last year or so I've been working with some wonderful humans on Paper, a super simple way to quickly share ideas with your team. We're about to start sending out more invites, so make sure you sign up for the beta at dropbox.com/paper.
These days I use Paper constantly to share everything from early ideas and sketches to full design specs (complete with my Sketch files) - getting feedback from my team every step of the way. I really hope you'll enjoy using it too.
A ton of people have been instrumental in shaping Paper, and I specifically wanted to call out Tony, Linda, Nick, Dave, David, and Jeremiah for all the love they poured into the interaction and visual design of this product.
One last thing - you can read more about it on Wired, Engadget, and Fast Company.