Witeboard lets you create quick sketches on desktop, tablet, or phone in a few minutes and collaborate with your team real-time.
Just go to witeboard.com, make a quick sketch, grab a share link and send it to your co-worker. You don't need to install anything nor create an account.
It's the fastest way to collaborate real-time with your team.
UPD' 2019: RealtimeBoard is now called Miro.
A whiteboarding platform for distributed product teams with a growing set of add-ons. Customize it to various use cases (from Agile to UX) and make it a part of a seamless workflow with the most popular tech tools.