Is flirting in the work place a good thing?

With equal numbers of men and women working alongside each other some form of flirting is bound to happen. Does flirting reduce productivity, cause workplace drama or friction or in some cases ruin marriages? Maybe flirtatious behavior is a good therapy for all of us. Crappy job? Crappy paycheck? Crappy boss? Don't worry we can still enjoy a good flirt session!
What do you think? Have any experiences to share?