Check out this site
www.shadowpeople.org/
It has tons of stories, one of them being mine.

My closest in age brother and I both could see shadow people when we were young. They would in classical style play on our peripheral vision never allowing us to view them directly. As I became older a time came I didn't see them anymore but now my childen can see them including the "Hat Man" I have some psychic ability and I am encouraging them to explore their potential as all children are inherently psychic. I should think your ability to see them is related to your development in this area. As you have probably read the cloaked entity with the red glowing eyes is the most frightening of all seen and it is suggested that all these enitites be they interdimentional or on our plane feed off negative emotions like deprression, anger but especially "Fear" The hat man is seen in a 1930's style Fedora hat and is usually looking down at the ground with his arms hanging at his side. So common is this that when I Googled a picture of the hat man for my kids to see they were quite shaken as they said the picture is exactly what they are seeing. The cloaked figure with glowing eyes appears to people who have been asleep and are startled by his silouette form. All eyewitness say he is he evokes a great sense of fear and apperas to be feeding off this(A form of energy vampire?- perhaps tied to our ageless sense of presence, the incubine/ sucubine demonic like creatures that are said to come in the night to haunt us) With all string theories now united under a single banner called "M" Theory one of the many goblins to come out of this idea is possibilities of infinite universes, each with slightly different versions of you, some without you at all, the closest one being close to your skin than the clothes you wear! Should this theory prove correct I could imagine it offering explantions for all kinds of seemingly, crazy, unlikely encounters so why not shadow people. Wouldn't it be ironic if they are the normal state of existance and we were the anomaly intruding on their existance? Truth might just be stranger than fiction!