Back in around 2007/2008 I was round my brother's house sitting with my sister-in-law and my niece. We were sat in the lounge just chilling, talking, watching TV etc. And generally just having a nice relaxing time.
I was sitting facing the windows and the doorway leading to the rear garden and kept seeing the security light going on every few seconds (it would come on, go off and immediately come on again). At this point, I thought it's either a cat or a fox walking about.
After about half an hour, the security light was still coming on and off repetitively. At this point I made my sister-in-law aware of the light and what it was doing. She replied back, "It's probably the ghost" (or something along those lines).
I laughed and dismissed it as her having a laugh and winding me up, but then I started seeing a shadow walk past. The shadow was of a human figure and it went across the brick garage outside, it was also approximately between 5'-10" and 6'-2".
I then thought, "My brother's not home for a long time yet, and my other nephews weren't around the area at the time either." Again I let my sister-in-law aware of the shadow I saw, and she laughed and said something like, "Yeah it's the ghost". I again laughed, but could tell she was serious.
At this point she then told me that my niece's MP3 player would randomly play sometimes for no reason. She then asked my niece where her MP3 player was, to which my niece replied, "It's on the dining table." (The dining table was about 10ft away to my right just outside the lounge). Now between 30-60 seconds later, the MP3 player turned on and blasted out music!
To this day, it's strengthened my belief in ghosts (I'm very skeptical about everything) and to be honest, there was no fear or "scary" parts about this experience... It felt as if whatever it was (supposing it was a ghost), was just there to have a walk around and make himself known.