Thriller Paranormal Activity has passed the $100 million mark at the North American box-office, off of a $15,000 budget - already making it one of the most profitable movies of all time while still pulling in crowds. The flick started with midnight screenings throughout America, and allowed visitors to its website to choose where it was screened next. Buzz happened in abundance and word-of-mouth has now propelled it to mammoth hit status. You can see the hugely effective trailer here. The film is previewing today, Friday the 13th, for one day only, then opens on November 25th.