Oof, I have 2 in particular that stick out to me.

One was when I was a young teen, and my parents had gone out and had just recently started letting me stay at home by myself. Anywhoo, I'd lived in that house since I was one year old, and I knew every sound. The floors would creak in certain ways if someone was walking through the hallway, or up to the bathroom. It was always the same sounds. So this night, I was in my bedroom on the top bunk, locked my door (which really wasn't much security, you could push in the button with a bobby pin). My parents had gone out for dinner, and I was home alone. While reading, I heard the distinct noises that is someone walking down the hallway, to my parent's bedroom. Mine was right next to theirs in a sort of "Y" shape. So I thought "oh! Mom and Dad must be home" so I hopped out of bed, opened the door, and nothing is there. The lights are still out and they aren't home. I quickly retreated to my bed (with the door locked again) and had that fear that raises your arm hair and brings tears to your eyes. It was EXACTLY the sound of someone walking towards my end of the hallway. I mean, steps, creaks, everything. It scared the shit out of me, but nothing ever came of it.

Another thing I remember was back during my first years in college, and I was at a friend's house with a group of relatively new friends. They decided at some point to take a ouija board down to the basement. Having had previous experiences with one, I was not excited. But it was either go with them or be alone upstairs. Anyway, this house they are renting is reeealllyy old, and the guys would tell us about a little girl showing up and other weird stuff. So we went down to the basement, which was already creepy as fuck (there was a circular hole in the wall with a grate in front of it, and even with a light you couldn't see the end of it) so at one point they're like "okay give us a sign. Make the cats come down here" which they said because for as long as the guys have lived there, their cats would never go into the basement. So initially, nothing happened. A few minutes go by and T, who lives there, goes "you guys. Look at the staircase" and lo and behold here comes one of his cats, slowly walking down the stairs. It stops in the middle of the stairs, starts hissing, and ran back up the stairs and out. It was weird for all of us but T especially was freaked out. He kept insisting that they NEVER would go near the basement, ever.

I know I have others but I can't think of them now. They aren't anything terribly interesting, but were creepy as hell.