Busycal Calendar App (iOS) Was $2.99, Now Free

I have (and like) the Mac version and at this price it's definitely worth a look at the iOS version. Expiry unknown but probably after Thanksgiving.
Official spiel:

BusyCal is a powerful, flexible calendar app for managing busy schedules, events and to dos.

BusyCal's unique features include customizable calendar views, integrated to dos, meeting scheduling, travel time, maps integration, natural language input, tags, alarms, search, weather, moons, birthdays, anniversaries, graphics and more.

BusyCal provides reliable support for iCloud, Google Calendar, Exchange, Office 365, and other CalDAV servers, enabling you to sync and share calendars with other Macs and iOS devices running BusyCal or the built-in Calendar app.