My first summer after highschool, I worked for my neighbor. He had a contracting business that mainly did light remodels on houses. Painting, general carpentry, basic landscaping, building decks, stuff like that. The usual crew was this guy, his partner, myself and one or two of my friends, and a general laborer or two, depending on the size of the job.
About halfway through the summer we got a job to do some cleanup on a house a few towns over which had been neglected for a while. Repaint inside and out, fix some squeaky floors and water damage, clean up the yard, etc. It was a decent sized house, and needed a ton of work, and the estimate was that it would take about a month to do it right. The homeowners had no problem, as they were not living there, and were planning on selling the place. Everything inside had already been cleared out (for the most part).
The first few days we spent just clearing brush and stuff out of the yards, so we could get equipment in to work on the exterior. Once that was done, we split off into two crews, one scraping the outside of the house, and one doing work on the inside. It was the summer, and the place did not have A/C, so the easier job was the work outside, and we would rotate who was in and who was out.
To give you an idea of the layout of the house. When you walked in the front door, you had large room off to your immediate right and left. Straight ahead of you and to your left you had a staircase that went up to the second floor, to the right a small bathroom, and then straight back to the kitchen and another large room. Upstairs you had 4 bedrooms and 2 bathrooms. There was only one staircase to the second floor.
We started in the front rooms, and within an hour or so our radio started acting up. It was an older boom box type thing, with a manual cassette player, and the knob with the slide for tuning the stations. In other words, it was all mechanical, not digital. At least 3 times, the station changed on its own, from 102.7 which we were listening to, to other random stations (sorry, no creepy oldies music or anything). What is interesting is when it changed stations, the station it would end up on would be perfectly tuned in, and the jump between stations was very quick, much quicker than a person could turn the knob and tune in the station so well, and then get away from the radio without being noticed, like, a seconds time, just enough time for the slide to traverse the distance to the other station. No, the radio didn't have the mechanical station presets.
At least twice when this happened I was in the room, and while my back was turned to it, the radio was in a location where it would have been damned near impossible for someone to get to it, turn the station and then get out of there. It was not by a window either. On a few occasions the volume would go WAY up, up beyond a point that I thought this thing was capable of producing. We then moved the radio to a different room, blaming it on bad power, and the problems let up.
Other strange things: Lights would go on or off while you were working, including our own portable floodlights. It wasn't the power was cut or anything, but the actual switch was thrown. You could also hear footsteps above you when you were sure nobody was upstairs.
The final kicker, as we were wrapping up the work on the place, I was replacing some molding in a second floor bedroom. I had a large heavy steel toolbox, with a bunch of tools in it, that must have weighed 30 or 40 pounds. One of those big craftsman jobs. I had finished off most of what I was doing, and had most of my stuff put away when our lunch showed up. It was raining outside, so were all sitting in the main entrance way by the stairs, in fact, myself and another guy were sitting on the stairs. EVERYONE was accounted for. By this point we were all always joking around how we were working in a haunted house, due to all the strange stuff that was going on, but no one was taking it real seriously. Everyone was pretty much convinced that it was the combination of an old house, our imagination, and probably a few of us screwing around with each other causing the stuff. Mid conversation about this, there was a giant crash from upstairs. One of the dudes freaked and just ran for the door. Myself and the dude sitting on the stairs next turned and went up the stairs. At the top of the stairs you had a clear view of the entrance way to all of the rooms, so in the 3 seconds it took for us to climb them, nobody would be able to get out of a room without being spotted.
Inside the room I had been working, my heavy metal toolbox had been tossed across the room, its contents scattered. The time from when it happened to when I got there was so short that stuff was still rolling around. Again, this was a 30-40 pound toolbox, which was sitting on the floor, and had been clearly tossed a good 10 feet. We checked the other rooms and of course found nothing. To go out the window (which was closed as it was raining) would have been a 15 feet drop into some nasty bushes. No ladders were up on the house, or even off the truck for that matter that day, due to the rain. Everyone working there was sitting with us while we ate, and nobody could have gotten past us and down the stairs while we checked the rooms, as there were people watching the stairs.
It was pretty damn scary, and the final couple of days of us working there everyone was really on edge. Nobody would go into rooms alone, and you could tell everyone was pretty much scared shitless.
The boss mentioned the goings on to the homeowner who was just kind of like "ehh whatever". A few years later, the place burned to the ground, and one of the guys I worked with that summer, who now lived in the town, sent me a story from the local paper. It turns out that the previous owner who lived there was a shut-in type person after his wife died a decade or so prior, didn't ever really come out much/do much, which explained the neglect. He had died about a year prior to us working on the house, but nobody found his body for at least 6 months. The people who had hired us was his estranged sons family, who had inherited the house and were trying to sell it.
The house had changed hands a couple of times in the several years after we had worked on it, nobody ever staying very long, and it was growing a "haunted" legend in the town.
In the interest of brevity, I left out some of the smaller parts of the story that were strange, or could have been explained away easier, but suffice to say, some weird stuff was going on while we were there. I'm not one that really believes in ghosts or anything, but I have no way of explaining some of the stuff that happened there in any rational way. Thinking about it still gives me the chills. Nobody was aware of the story behind the house when we were working there, and you could tell after the toolbox incident everyone was truly on edge.