Airliners documentation (Matt Zagoren)
Boeing 727 (B727 100-200)

Boeing 737 (B737 200-300-400-700)

Boeing 747 (B747 100-200)

Boeing 757 (B757 200)

Boeing 767 (B767 200-200ER-300)

Airbus A300 (A300 B4-203)

Airbus A320 (A320 232)

Airbus A340
Links
Some links and documents that provide technical data on some aircrafts and aircraft parts. Some of them also include very professional data as regards aircraft capabilities, performance and handling.
FAA Type Certificate Data Sheets (FAA)

Boeing airplane manuals and product bochures (Boeing Company)

The Unofficial Airbus Study Site

Airbus Aircraft Characteristics (Airbus Industry)

The Evolution of modern aircrafts  (Langley Research Center)

The Incomplete Guide to Airfoil Usage (D Lednicer)

AirNet web site (general interest)

Sm@rtcockpit site
Aircraft data