Yep. I have a USB extension cable or two, which is handy (dragging your laptop of a table onto the floor is *not* fun

Basically, you use the software that comes with your camera - check to se if it has a remote shooting mode.

Dunno about Nikons - for my Cannon, I simply turn the camera on while connected via USB, and run the camera software and select "Remote Shooting" - there's no special mode you have to put the camera in or anything like that. YMMV of course.

Then all that happens is when you take a shot, it's beamed to the computer, rather than saved onto the memory card, and can then be displayed on your monitors.