"My activity" page that would support admins reviewing a named user's activities/changes

It would be helpful to have a UI to review activities of/regarding a selected user(s).

If a subject(s) could be selected and that user's activities could be reviewed would be a helpful feature for troubleshooting user driven changes that might have affected a group or another subject.

Also, if the named subject could be used to find "activities that affected that user" that would be helpful too.