The developer of this program did a good job laying out the feature set of this calendar. It is highly configurable, customizable, and easy to install. I have really not found anything that can't be done with it. And I have looked at and tried a lot of calendars, both open-source and $$$$, to find the "right" one for this non-profit org. website.
There are many other web calendars (competition is good).
Plans tries to be easier to use, more flexible, better-looking, more powerful, faster, and cheaper than all the rest :)
Feel free to compare: