While installing the latest patches for my OS, I remembered reading about an extension for my mail client. I hopped over to the Mozilla site and grabbed a copy of the 0.5 release of Lightning, a calendar plugin for Thunderbird (there also is a standalone version named Sunbird). I never used nor needed a calendar for private use, but after using it extensively at work where I'm forced to use the Outlook calendar, I am convinced it has benefits. So when I learned about the Lightning plugin, I just had to download it and try.
Installation is easy as hell, and I already added my first "event" to the calendar. Time will tell whether or not I actually will use it, but as I open my mail client frequently, I think the current setup is the best approach to find out.