What are some alternatives?
When comparing Microsoft Hotmail and Teamup Calendar, you can also consider the following products
Calogic - CaLogic is a feature rich, muti-user, open source web calendar.
Google Calendar - Spend less time managing your day & more time enjoying it
CalendarX - Get a calendar your audience can follow
Outlook - Organize your world. Outlook’s email and calendar tools help you communicate, stay on top of what matters, and get things done.
Kin Calendar - The simple and connected calendar
iCal - In Calendar on your Mac, subscribe to calendars published or shared by others.