Sumatra, there are a few possibilities:

• You are hallucinating. I'm not suggesting there's anything wrong with you, but your imagination might be so strong that when you anticipate or think about your husband coming home, you can "see" him in the driveway, although he is not actually there. Your imagination creates a very real illusion in your brain.
• You are having precognative episodes; that is, you are seeing something before it actually takes place. You are seeing a future event.
• You are seeing a psychic recording. The action of your husband coming home has somehow been recorded on the environment, although he is not actually there physically. This recording is then played back -- perhaps triggered by your anticipation. This kind of recording may be responsible for what is known as residual ghost phenomena, in which the action of a person, now dead, has been recorded in a location and occasionally plays back to be seen or heard. (A common example is the sound of a ghost walking up a stairway at the same time of day.) If such recordings can occur with those who have died, why not for the living?

Anyone else have any ideas?