Heated Office Seat

If you've ever driven in a car with heated seats, you know how comfortable they can be on an achy back.  Why not have the option to sooth your muscles with a heated office seat.  It would be battery operated and plug into the wall for a recharg at night when you go home.  I've seen heated massage chairs and heated cushions you put over your bucket seat but still haven't seen an official rolling office chair that warms your tush.