Perhaps the most important part of any graphic workflow is color management. A colorimeter should be up there with a camera and a lens on your list with of equipment to buy. Without one there's just no way to ensure reproducibility of your photos. Colorimeters are relatively cheap nowadays and even the basic ones are more than enough for discerning photographers. If you don't have one I recommend going and picking up the ColorMunki or ColorMunki Display right now. These are great inexpensive colorimeters that work well and last many years. My ColorMunki Display works fine with Xubuntu 14.04 and I imagine most USB colorimeters would.

Once you have the hardware you'll need the software. On Ubuntu based distributions this is very easy. Somewhere between falling off a log and screwing in a lightbulb. You can either used the built in display calibration tool in regular Ubuntu or install dispCalGUI via the Software Center or web download for Kubuntu or Xubuntu. If you are using one of the Ubuntu derivatives as I am you'll need to install whatever bridge you need for the desktop environment and colord if it doesn't have it by default. For Xubuntu and XFCE that's xiccd. Again not terribly hard. This is so the resulting profiles can be loaded by XFCE/Unity/KDE/etc. In standard Ubuntu you won't even have to do that much if you use the built in tools, however I recommend trying out dispCalGUI anyway as it supports more features of the colorimeter's hardware, such as ambient light detection.

As far as I can tell there's no calibration reminders in dispCalGUI like the X-rite software. I may have missed it somewhere though. I just put a reminder in my calendar to overcome that problem.

All in all display calibration is pretty simple in Linux. If you can do it on Windows or OS X you can do it on a modern Linux distribution. The whole process is about as hand-holdy as it gets.

Next up I'll go over organizing, tagging and metadata handling.