A particularly impressive experience I've had with a Ouija board was last year with an ex-boyfriend; I was introducing him to it, so I made a really nice set up with three silver animal skulls & a candelabra. We spoke with an entity calling themselves Lekme, who declared themselves to be a deceased young child and claimed to have been around for a thousand years. They told us about the future & secrets from the past. The boy asked "How do we know you're real?" It answered "skull". I told him to pick up the largest, middle skull. After a moment of holding it, he turned to me, shocked; "feel how heavy this is." I took it, noting much more weight than I'd have expected. "The spirit made it heavy in my hands, I felt it." Soon after, we finished up and said goodbye. He used to doubt the occult, but never again.
Another (less impressive) occasion was much earlier on in my youth, one of my first times actually using a Ouija board. I was sitting in my basement aside red candles, and I opened the board; I asked "What is your name?" The planchette just darted between "O" and "Z" over and over. I remembered some creepypasta I'd read years earlier (on the browser of my DSi) about a demon named Zozo who often came through Ouija boards, got scared, and said goodbye.
Very recently, I had an experience with some doubtful friends who came over. We sat around the board, put our fingers on the planchette, and I told someone to ask a question. He asked the board whether or not the spirit liked to smoke marijuana, and it got angry and said goodbye. Around half an hour later, the boy who asked became sick and left. I had been told that he remained sick for several days.
And those are all my notable experiences with Ouija. I've always done it inside my house, I've never had the time to go to out somewhere with more activity and try. But I have done quite a few dark things in that basement of mine, it's bound to have a some kind of entities in there... haha.