Printing across subnets
What great timing! I was pulling what's left of my hair figuring out how to get 5 different laboratories on different networks to share their printers. Thanks to LinuxPlanet's Carla Schroder for providing a great (and timely!) tutorial on how to setup printer sharing across subnets, I get to keep what's left of my hair! 
You might not notice it but this tutorial highlights how command-line configuration is a tad better than any of the GUI tools.
Image from Flickr:Tawalker.