I have had experiences throughout my entire life. My family has lived in the same two houses since the early 50's. We have only had one person to die on our property since then and it was my grandfather.
When he was alive he would go around the house and turn off lights that he thought were "unnecessary". When the music or TV was too loud for his liking he would bang on the wall and get us to turn it down. Strangely enough these things still go on until this day.
The Christmas after he died was when it all started. My grandmother liked to sleep on the couch out in the living room so she could fall asleep with the TV going. She would also leave the Christmas tree plugged in so there was more light in the room. Every morning she would wake up and the plug would be out of the wall and no where near the outlet.
My brother and I will be watching TV in my room and it will suddenly turn off. It's not just my TV that does it. My grandmother will fall asleep with the TV on and it will be off the next morning. We have played with the remotes and even tried to figure out if our cats could have somehow turned them off, but there is no way that we can see that would allow them to turn them off.
The most recent thing that happens is when my brother is in his room at night, listening to music (which I will admit is usually too loud). Randomly throughout the night he'll have loud bangs on his door or the wall near his room. I have yet to experience this, and I must admit I'm not sure if I want to.
As I stated before this did not go on before my grandfather passed away so we are almost certain it is him. Before he died my Grandmother asked him to try and contact her or to watch over her if he could; so in a way, I think this is his way of communicating with us.