Andria Lynch sent us a quick way to hide all the x-refed layers when using the pulldown menu on the Layer Properties toolbar.  Open the Layer Manager and select the automatically generated x-ref filter so only your x-refed layers are displayed in the manager, then right click in the layer list (the name column) and click on invert layer filter. Click on apply and now when you're working in your drawing, the long list of x-refs are hidden and only the drawing specific layers are shown.

NOTES FROM CADALYST TIP PATROL:  This is a great tip demonstrating how we can change the way AutoCAD displays layer lists to us.  The layers are still there, they just aren't displayed in the list.  You can still work with them in the file.  To turn the layers back on in the list, open the layer manager, right click the name column, and click the INVERT LAYER FILTER button.  If on there will be a check mark on the left of it.  Clicking it again will toggle it off.  This tip works on any layer filter, not just the x-ref filter.