A quick one for the users. Now that Mozilla Thunderbird incorporates the Lightning plugin as standard, it's even easier to link up CalDav calendars to your mail client.
Firstly, in the Calendar view of Thunderbird, create a new Calendar. This will be the one linked to your CalDav Calendar. This will give you various options, like giving a nick-name to the calendar, and setting the colour of events synced to it.
The important one here is the CalDav URL field. This is where you tell Thunderbird to get all your appointments from. You'll find this in the Properties menu of the target calendar (right click to get the drop down). I use Open-Xchange (OX) to handle my mail and appointments, so it's the CalDav URL from here that I'll want to use.
Just copy and paste the CalDav URL from here into the field in Thunderbird and you're done! Click through to finish, and you will now see all your appointments appear in Thunderbird.
Thunderbird is an Open Source mail client from Mozilla, the same people behind the popular browser Firefox. It is as powerful a client as you could ask for, and, being platform independant, will run on Windows, Mas OS X, and (of course) Linux. That it supports CalDav gives it a the ability to integrate calendar entries with numerous mail servers, including iCal Server, Oracle Beehive, Zimbra, Zarafa, and SOGo amongst many others.