I absolutely love Fantastical. It's a wonderful way to manage my week-to-week activities via my iPhone, and there's a desktop client as well. Fantastical uses "real" language when it comes to adding appointments to your calendar. This means that I can simply type: Dinner with the wife next Wednesday at six, and it knows to setup an appointment on March 13 at 6PM. That's really just the beginning of how useful Fantastical is, but this isn't meant to be a review of Fantastical, this is a tutorial that shows you how to link Fantastical to the stock Calendar app.
How to link Fantastical to the stock Calendar app icon