Out of all the Lost mysteries that have appeared over the course of the series I can still remember Sayid running away from Rousseau and hearing the whispers for the first time. Persoanally, the whispers played on my mind the most out of any mystery that I have seen on Lost, even the smoke monster. Probably because we have actually seen the monster, even though we don't know what it is, we can at least put some kind of 'face' to it. The whispers are truly an unseen mystery and I hope that the producers address the whispers and answer what they are. I did read somewhere that they aren't going to which irritates me because obviously there was some reason behind them when they originally appeared. The other thing which I mull over often is who was in the other outrigger when the island was jumping through time, that really makes me wonder. What is your most anticipated mystery answering?