I have 8 calendar apps on my iPhone. I've been using @getcalpal for the last week and it's the first one that's really made a difference in my productivity.
When you create a CalPal event and invite your friends, you can start a message thread with the event group. This eliminates the texting, emailing, FB messaging, calendar inviting back and forth that I previously had trying to organize events.
CalPal's creators are @rahuljaswa and @michaelbachand.
Check out the app!
The Twenty Minute VC