I most certainly do believe in ghosts, and in fact had the experience of living in an apartment that was "haunted" for about a year.
Playful ghost, used to tease us with harmless pranks such as moving things we had JUST put down, turning off lights we'd just turned on, and the funniest instance was on day I was home alone and turned off the tv in the living room, put down the remote and walked into my bedroom. Then the TV popped back on. I went out, shut it off again, and started to go back to the bedroom. On goes the tv again. This happened for 5-6 times, each time I'd put the remote down and start to walk back I wouldn't get quite as far. Finally I got the hint, laughed and said "Ok, that was funny. good job" and just "felt" like someone was smiling, then it stopped.
Many such instances happened in that place, and about 6-7 different friends/family experienced these "occurances". Also we had many pets in that apartment, and there were times when you just knew he was around, because all the pets would just stop and start staring at the same place and follow the same motion. (funny to see 4 cats and 2 dogs just freeze what they were doing to look at "something")
One night the front door just opened on it's own, and then shut. My roommate and I just stared at each other and said "he left", and nothing further happened after that, and the place just had a different "feel" to it after that. I spent a lot of time alone in that place, and only after that night did I ever really feel.. alone. I guess we bored him after a while and he moved onto a different apartment? (and I did always say my roomies voice was shrill enough to drive out the dead.. perhaps that wasn't an understatement
)
A friend of mine also had an experience with a less than playful visitor when he happened across an OLD wooden Ouija board (not the cheap Parker Bros. thing, an actual wooden hand carved one) and thought it would be cool to bring it home. For the week or so that board was in the house, objects would start appearing in strange places. (the ashtray would be on the coffee table when you'd leave the room, and come back to find it up on a high shelf, or teetering on the top of the television etc, my friend and her boyfriend started being plagued with nightmares, and a less than pleasant feeling began to encompass the house... we ended up destroying the board, and all went back to normal)
I've had too many of such encounters to not believe they're here with us. And I know some people might think I"m crazy... but the friends and family that shared these experiences with me, know that I'm not.
It's kind of funny that this thread popped up now. Just last week my cat (who I've had since that old apartment) just stopped in his tracks and started mewing at the bathroom, eyes bugged out of his head, the same as he used to act when that ghost was around, and the hairs stood up on my neck. My new roomies thought I was crazy.. but Midge and I know that a ghost just passed through.