Is it Ever Ok for Someone to Take His Own Life?

Were covering a story tonight about a couple who committed suicide together.  When Sir Edward Downes and his wife Joan learned that she had terminal cancer, they traveled to a clinic in Zurich and drank a fatal dose of barbiturates together. 

Some have sharply criticized the clinic for its openness to patients with a vast array of ailments – and its openness to those who aren’t ill like Sir Edward.

What do you think?  Is it ever right for someone to take his own life?  Should someone with a terminal illness have the option, and should a member of their family be allowed to die with them by choice?