A friend of mine, L, lived in a haunted apartment and I often experienced things when there with her. She had a ghost cat which looked like a brown-gray tabby that I would see out of the corner of my eye, but would always disappear. After she adopted a white cat, or the cat adopted her, the ghost cat changed its appearance to look like her cat. That was disconcerting- I would see what I thought was her cat walk into the bathroom out of the corner of my eye, but it then would be in the living room.
Once when we were hanging out together, we heard a man's voice call her name from within the wall. This was an exterior wall three floors up. We looked at each other and I said 'I heard it, too'. She just nodded and we continued our conversation. L talked about things that happened when she was alone, like feeling someone spooning her while she was in bed.
I lived in an apartment with my ex-fiancee, P, and another friend J. This apartment had been occupied by several members of the pagan community- someone would move out and someone else they knew would move in. A lot of magical work was done in that apartment- and in L's too, now that I think about it. We were on the third floor, which was the top floor. Something was up on the roof, and I would often hear it running around up there. It sounded about the size of a child- maybe 6 to 8 yo? The access to the roof was padlocked from the inside, and we didn't have a key. Once I was in the shower and I heard it running around. I yelled out to it to go away, and it came to the corner of the building where the bathroom was. It leapt up and down repeatedly, until I told it I was sorry I yelled.
We would regularly find things moved around. I had a glass bobbing bird that would bob up and down if you dipped its beak in a glass of water. It got knocked off the windowsill and broke. A few times, I glimpsed a gremlin-like thing out the kitchen window- it was outside the balcony, gripping the ballisters and leering at me.
Oddly enough, all this happened when I lived in the Boston area. I moved to Texas fourteen years ago and haven't had a single experience. I'm no longer a practicing pagan, though.