The 1-series cameras can save the current camera settings to a card, up to 10 sets, and load them on demand. The 1D X is the first 1-series body to feature Camera User Settings (C#). The combination makes for a powerful way to manage groups of settings, since the C# settings are saved and loaded along with other settings.
For example, I have one Outdoors set, where C1 is for landscapes, C2 for static birds/wildlife, and C3 for BIF. I've got a Family set, C1 for tripod shots (10 s timer), C2 is for static shooting (min 1/125 s, manual AF point selection), C3 for moving kids (1/250 s min shutter, 61-pt AI Servo), etc. Another set for manual AFMA with the FoCal settings.
I store them all on an old 2 GB CF card carried in the pocket of my Blackrapid RS-4 strap, with a backup on my computer.