Usage time check for Panasonic 
The Official "How to Check the Hours Used on Your Plasma" Thread:
2011 Models : _X3 / S30 / ST30 / GT30 / VT30
2010 Models : _X24 / C2 / U2 / S2 / G20 / G25 / GT20 / GT25 / VT20 / VT25
    * Press and hold the {VOL -} button ON THE PLASMA TV.
    * Then press the {INFO} button on the remote control 3 times.
    * "Start Adjustment Menu" message will be displayed followed
      by the Service Menu after few seconds.
          o ADJUST {Picture Adjustment}
          o WB-ADJUST {White Balance Adjustment}
          o OPTION {Option Setting}
          o V-SUS {V-SUS Adjustment}
          o AGING
          o SRV-TOOL {Service Tool}
      {1} & {2} buttons move through options
    * Press the {2} button once to select "SRV-TOOL".
    * Then press the {OK} button to access it.
    * Using the cursor keys, highlight the right side
      of the last item "PTCT :00.00.00.00.00" :
    * Then press and hold the {MUTE} button for 3 seconds.
    * Time and Count will be displayed in red color:
      __TIME = Hours : Minutes of operation.
      COUNT = Times the Plasma was powered on.
    * To exit, unplug the power cable.
      WARNING BY BRUZZI: The {VOL+} and {VOL-} buttons are used
      to change values while in the Service Menu. Make sure not to touch
      those buttons when navigating menus / sub-menus.