no offense, but no one can predict when the world is going to "end". i believe that when the planets align in 2012, we will have more than the usual natural disasters but that will be the extent of it. and if it does, it's our own fault because we don't take care of our precious planet.
The bible does tell us the signs to look for though. You are right no one knows when it will happen but if you read the bible it will tell you the signs of Jesus's coming.