Can I assign "U" for "undo"? I come from a very different CAD background with years of muscle memory with other tools that I would like to use with Blender.
Right now, I would like to associate the key U with "undo."  However, if I assign it in User Preferences, and re-assign "Make Single User" (in "NLA Editor" group) to a different combination, I still get the "Make Single User" menu when pressing U.

Is there a way to re-map "undo" to U?  I've successfully mapped ShiftZ and CtrlZ to zoom-out and zoom-in, respectively, for what it's worth.  (note: the CtrlZ to zoom-in, which I've grown accustomed to, is the particular qualifier why I'd like another key to "undo".)

I'm currently using Blender 2.75a under Arch Linux.
This is because the shortcut you re-assigned only applies to the Non-Linear Animation Editor.

To find all conflicting shortcuts, search based on key binding instead:



There are U shortcuts in the 3D view (both in object mode and edit mode) which call the call_menu() operator. This is different from the NLA editor, which just runs nla.make_single_user() directly when called since it has no options.

Disable or re-assign the conflicting shortcuts, then it works as expected.