Adding scale, offset, units metadata to geotiff

FYI:
Martin Daly and I are discussing adding this tag to the thredds server geotiffs: 

 http://www.awaresystems.be/imaging/tiff/tifftags/gdal_metadata.html
this would allow us to put out 8-bit geotiffs, but clients could convert back to floats, using a scale and offset. 
We can specify the units also!!

Any comments on this idea are welcome.