SmartCal lets you choose and mark calendars as favorites by clicking on the button: You may or may not want to subscribe to these calendars. You might just want to keep tabs on a particular calendar, and add events from the favorite calendar to your home calendar. That way you don't see all the events on the calendar, just the ones you choose.

You can see all your chosen favorites on the My Calendars page which you can get to from the menu bar. Your favorites may be your friend's favorites as well. Be sure to recommend them!