Update November 2008
I am a student at Humber College. I've read up on the history of the buildings and "sightings" that others have reported. I am fortunate enough to have had access to the school's tunnels for 3 years now. I can quite honestly say that I haven't experienced a thing down there! I even went down there with another person in April of last year, and we explored the whole tunnel, going to every building. There are rumors going around campus that there are old hospital stretchers and straight jackets kept kept in the tunnels, which I can assure anyone, there isn't! So let's put that rumor to rest!
I did have one strange experience, however. During midterms in second semester, I had to go to J Building - of which I had never been - on an assignment that involved me talking to Humber students and having them fill out a survey. Because it was a Friday where most students have the day off, AND we were in the middle of midterms, the building was very quiet, with hardly any students around. However, I was instructed to be there for a full 3 hours! While I was sitting in a chair, with nothing to do, I found myself almost falling asleep! This is when I heard a humming noise. It sounded like a young child humming "Ring Around The Rosey" but I can't say for sure if that was the tune. I woke myself up, and straightened up in my chair, to listen more closely and make sure I wasn't hearing things - but the humming continued for almost a full minute. As soon as you walk into the building there's a hallway of offices, and only one was occupied by a woman, so I asked if it was her that was humming and she said she wasn't. Also, there are only 2 classrooms on the main floor, where both doors were closed, so you couldn't even hear the profs speaking to the students.
I haven't gone back to the building since - mainly because I have no need to. But I did do my research and found that the building next to it is K Building, which has not been renovated yet, and it was formerly the Child and Adolescent Unit.
Our thanks to the witness for sharing this experience with us.