X (Twitter) - Connect with your friends and other fascinating people. Get in-the-moment updates on the things that interest you. And watch events unfold, in real time, from every angle.
Google Calendar - Spend less time managing your day & more time enjoying it
Taskful - Deadlines, meet your match.
Mixmax Calendar - The fastest way to schedule meetings with anyone, anywhere
PopDo - A quick task list for your Mac menu bar
Sunsama - Calendar and scheduling for teams