One of the biggest arguments I hear from users on why they need to be Administrator or Power User is the need to change the time, date, and/or time zone on their laptop when traveling. Aaron Margosis points to the KB article 300022 which describes how to allow non-admins to change the date, time or time zone.
"First, you need to have the “Change the system time” privilege. Run “Local Security Settings” (as admin), navigate in the left pane to Security Settings \ Local Policies \ User Rights Assignment. Double-click on “Change the system time” and add users or groups. You can also specify “INTERACTIVE”, which will allow whoever is logged on to the computer to change the date and time. You need to log off and back on for the change to take effect.
That gets you past the error message, and lets you change the date and the time. However, attempts to change the time zone will fail silently, with no error message. To change the time zone, you need to change the permissions on this registry key:
According to my testing, here are the permissions you need: Query Value, Set Value, Create Subkey, Enumerate Subkeys, Notify, Read Control. KB 300022 says to grant “Delete” also, but as far as I can tell, that does not appear to be necessary. This change doesn’t require logoff/logon to take effect."