This is one of my favorite components. There are so many types of websites that can benefit from a calendar on their website. JCal Pro/ JCal Client is a great solution. They've released a beta version that now allows you to have multiple calendars. Maybe your site is for your church and you have many departments with multiple events. You can now separate these out so they're less cluttered. If you add on a separate Access Control Level component you could even regulate who sees what on your calendar.
JCal comes with a couple of modules I really like. One is a mini-calendar and the other is the latest events listing. This is a great way to get people to explore the content of your site.
Way to go! Check out their site here: http://dev.anything-digital.com/