There's a new forum on Darkshade, all about jumping the shark.  In it we will discuss the moment any given TV series drops in quality.  After that point it loses whatever merit it had earned with the audience.  http://darkshade.homeip.net/cgi-bin/forum/Blah.pl?b-sharkjump/

Did a show you enjoy take a turn for the worst?  When did it happen?  What was that moment which ruined the series for you?