In 1872, two "air shafts" were found in the Queen's Chamber.
This is a collection of documents about them downloaded from the Web and the Wayback Machine.
The Upuaut Project (1992-1993, originally at cheops.org)
The Mystery of the Hidden Doors Inside the Great Pyramid
The Djedi Project (PDF)
Into the Great Pyramid (2003 video documentary)
Discovery News :