Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Future - Calendar events around the clock
Wiplo - The easiest way to organize and run your business workflows.
Event Calendar App - A simple, easy to manage, way of displaying events
Toby for Teams - Better bookmarks, now with collaboration baked in π
Loxi - Easily add an events calendar to any website.