Yahoo Calendar is Yahoo's free day, week, month, and yearly planning tool. Users with Yahoo accounts can create their own calendar for free and share it with others. Creating new events is a simple affair. Anyone can link up an event or task to several e-mail addresses and get reminders on a variety of devices and services including Yahoo Messenger or on their mobile phones.
In addition to its planning roots, Yahoo's Calendar doubles as a task scheduler where users can set priorities and make their own to-do list complete with time zone control and highly customizable due dates. There's also a huge directory of events you can add-on to your calendar such as U.S. holidays, horoscopes, and daily weather reports.
Winner: Yahoo Calendar (Calendar.Yahoo.com)