Looks like a useful thing to keep more pins alive, got to be good.

Leon of test rom fame has published a few suggestions, but these are far less elegant and perhaps beyond the scope of most of us.
Mike's offering is much neater and more elegant. 

http://home.scarlet.be/~cv006274/ledbal/eled.htm  for Bally
http://home.scarlet.be/~cv006274/dispwill36/edispwill36.htm  for WMS

Leon suggests supplementing the 5V supply.