Upon reading an essay on the Mad Ghouls website, I decided to take on the topic of gravity hills. The essay talked of an urban legend his father relayed to him when he was a small child living in New Jersey I presume. The legend including a jealous boyfriend who killed his girlfriend in cold blood and then fled the scene in his car. The apparition of the girlfriend made an appearance and pulled the guys car back up the hill. Of course, this woman supposedly haunts this hill 'til this day, reliving the same moment over and over. Even the stories of ghost children dying on railroad tracks has been associated with gravity hills. Although, technically, they don't work that way.
While some people believe they are paranormal in nature, it has more to do with an optical illusion than anything. It can trick you into thinking that a ball can really roll uphill or that you can stand at impossible angles. However, distortions in perspective and odd angles along with the shape of the surrounding terrain can easily fool the human eye and brain. You may think it has to do with some weird gravity anomaly, but trust me. In these areas, gravity is working normal as usual.
Despite the lack of the supernatural, no one says you can't still have some fun. Visit one of the many gravity hill sites across the world and test out your experimenting skills. To find one near you, the gravity hill entry on Wikipedia has a list for you to choose from.
Source: Paranormal @ About.com