I need an easy way to turn off the UCS icon in some of my drawings.  What's the easiest way to turn the UCS icon off?

Open the properties box (CTRL+1) without a selection set and you will be able to set UCS visibility and a few other options for the UCS in the "Misc." area at the bottom.  This is a lot easier than using the UCSICON command multiple times to set the individual settings.