Calendars and To Do lists are becoming more and more popular, and very often users have more than one online calendar, because they cant synchronize all of them to one master calendar.
Fusecal, promises to sync your calendar to any other calendar. " We sync events to your personal calendar program, and send you updates when they change. Keep all of the events, or hand-pick just the ones you want."
To make it work, you have to provide Fusecal with an URL to your master calendar, where you want all the other calendars to be synced and than have to decide which events you want to keep.
I use my cell phone calendar and have to tell you that in busy days, it comes very handy with all the mobile reminders.