Zofran
"This drug has saved my life at least once.  I took it when I was pregnant and had unrelenting morning sickness that wasn't helped by any other medications.  I'm now taking it again for nausea caused by severe pain (as well as the nausea caused in turn by pain medications, as I seemingly can't win on that one).  But perhaps most importantly, it was the only drug that got me out of opiate withdrawal when I had the stomach flu.  Without this, I would have been in the hospital because I couldn't otherwise keep anything down and without opiate therapy the withdrawal and the pain combined could easily have killed me.  The only possible drawback is cost; even the generic would be completely out of reach for someone without insurance."