Nikon D3X Manual Available for Download
This 17.84 MB PDF instruction document (Nikon calls it a "Guide to Digital Photography") for the Nikon D3X should prove to be a fantastic read, all 476 pages of it – be sure to download it!
Both printable and non-printable versions of the English Language D3X owner's operation guide can be downloaded.
The user guide is titled "Nikon D3X Digital Camera User's Manual" (the 17.84 MB Acrobat document that I referred to).

For copyright purposes, the printable version of the Adobe Acrobat PDF document requires you to input your camera serial number and agree to a license, while the non-printable version doesn't. You'll get the following dialog box if you try to print the password-protected, non-printable document:

The guide discusses the features of the D3X and how to use the camera, for instance, on page 392, there's a list of accessories that can be plugged into the remote terminal. The Phottix Cleon N8, a hybrid RF (radio frequency) wireless shutter release (trigger), is an example of such an accessory.
