I've been having this problem for some time now.

Every now and then, when I go to start my car...nothing happens. I turn it
all the way, it clicks once, then the radio and A/C come on. It doesn't
even ATTEMPT to start. When it does this, I jiggle the the the automatic
thingy on park, and then it starts, but recently that hasn't worked.

I took it to the dealer once, and when it got there, it started up just
fine! It's like the boy who cried wolf...

I have also replaced the battery.

If anyone has an idea of what it is, let me know.

Your 1995 Nissan won't start? Mine did the same thing, its a 1995 too. I
would drive perfectly normally and then get somewhere and attempt to start
it and, click, nothing but radio and battery-operating devices. This would
happen 1-3 times a year. Sound familiar? I solved this by putting my
foot on the brake, turning the key so the vehicle is on-even though it
won't start all the way, and gently swiping the tranmission gear shift
down to drive and back up to park(MAKE SURE YOUR FOOT IS ON THE BRAKE THE
WHOLE TIME). You may hear a click, and the next time you turn the key
(make sure its in park) it should start.

I am experiencing something sisilar with my 1993 and have posted my
situation. I will try your fix..thanks