Initial work on the Drupal version of the WHO-5 Well-Being Index has been completed and I've published a working beta version of the module on the module's Drupal project page.
While this is a working release, the module is not in a finished state yet. Plans for the near future include:
One major activity at the moment is digging through the research that has been done on the WHO-5 to ensure that the instrument on which the module is based has sufficient research basis to make it really meaningful as an instrument. So far, the results of initial literature searches aren't yielding as much information as I had hoped. If it becomes apparent that there isn't a significant body of research behind this instrument, I may end up retiring the module and searching out other options.