I've run into a couple of friends and such, especially since we're "local" (about an hour away.)
One was a family I used to teach at craft class at Michael's and used to wait on at my second job (they started at the classes, and then used to visit me later in the day for dinner at my second job) It was right when Finding Nemo opened at Epcot, and dd and I were standing in line when I see this family in a clam shell going crazy. They waited for me when we got off, and were pleased because they finally got to meet my dd. We actually ran into each other later that day at MK ... small world.
My favorite though just happened this past weekend. We went up to Disney to stay the weekend, and my parents were planning on coming up on Saturday to spend the day at MK for my birthday. We wanted to start the day at EPCOT, however, so we figured we'd call them after making our way through the food stands of the Flower and Garden festival. Imagine my surprise when I heard my mom yell my name in the crowded parking lot, and I turned around and they were about 10 cars and a row behind us. It all worked out perfectly, and was hilarious to us.