LCD and Viewfinder
Nikon D40 has a Fixed Type 2.5" LCD screen with a resolution of 230k dots. At only 2.5", the screen is on the smaller side and 230kdot resolution is lower than most of the recent models in this class.
D40 has a built-in Optical (pentamirror) viewfinder. The viewfinder has a coverage of 95% and a magnification ratio of 0.53x. 95% coverage means that what you see in your viewfinder while shooting will slightly be different from the actual image.
Max Shutter speed
Nikon D40 can shoot continuously at max speed of 3 fps
and has max shutter speed of 1/4000 sec
D40 has a built-in flash, and it also has a flash shoe to mount your external flashes too.
Nikon D40 features a Phase Detection autofocusing system.
Unfortunately Nikon D40 doesn't have Video recording ability.
Connectivity and Storage
Nikon D40 has a USB 2.0 (480 Mbit/sec) port to connect your camera to other devices.
Nikon D40 Features Compared to Main Competitors
You can download Nikon D40's User Manual here