I'm not sure that I believe in ghosts. I've never seen one, but I've certainly felt a sort of creepy energy around the place.
So here are some ghost stories from people I know. Two of them are complete skeptics when it comes to spiritual things, so feel like they must really believe what they've seen.
The green light
A relative of mine was sleeping in a house where a man had recently died. There were tins of dog food found in the man's bedroom despite the fact he had no dog and he had died elderly and alone in the decrepit, old villa. One night, she was lying in bed and a green light appeared on the wall. She thought she was hallucinating and so woke her husband. He could see it too. They watched the light slowly growing larger and brighter before it shrunk away to nothing. They checked to see if the light could have been reflected from outside but the room they were in had only one window and it faced out to many acres of farmland, no cars in sight.
Another relative of mine was out in the backyard gym when he stormed into the house and demanded his wife stop pulling faces at the window. She hadn't been and the gates were all securely locked so nobody else had been in the yard, either. They went to bed. An hour later, the doorbell rang. The husband sat up in bed, exclaimed, "My papa is gone!" then went to the door to receive the news that his grandfather had passed away an hour earlier.
The checked shirt
My grandmother was visiting from overseas. We were living in a (mostly-finished) home my father was building on what had once been a farm. I was terrified of our kitchen and refused to go in there alone. My gran told me that she didn't like the kitchen either but did not elaborate. One day, a man came to the door to check on rates or water or something. He mentioned that my father had built our house right where his friend, the farmer, had died many years ago. "Right where your kitchen is, actually!" My grandmother asked him if the man had been wearing a blue checked shirt and a hat. She continued to describe the farmer. Our council visitor looked visibly shaken and confirmed the facts. He had fallen over the front of his tractor and had died under one of the wheels.
So.. I'm not sure about ghosts, but I do think that when we die perhaps part a shadow of our spirit is left behind.
Or maybe we're just way more observant than we realise - anybody else see this guy on The View a couple of years ago?