This show seems to have had more guest performers win emmies than any other sitcom or drama:

John Larroquette
Edward Hermann
Charles Dutton
Alfre Woodard
Beah Richards
James Whitmore
and now Shatner and Stone
There's another male actor who won in 2001 but I can't recall. In virtually every season some guest player wows the voters and wins. Plus Holland Taylor, CAmryn Manheim and Michael Badalucco have all won, and of course David E Kelley won 2x.