YOU KNOW YOU'VE BEEN ON THE COMPUTER TOO LONG WHEN ...
                 (author unknown)

You are counting objects, and you go "0,1,2,3,4,5,6,7,8,9,A,B,C,D...".

You dream in 256 pallettes of 256 colors.

Asked about a bus schedule, you wonder if it is 16 or 32 bits.

Your wife says "If you don't turn off that damn machine and come to 
  bed, then I am going to divorce you!", and you chastise her for 
  for omitting the else clause.

You try to sleep, and think  sleep(8 * 3600); /* sleep for 8 hours */

You are reading a book and look for the scroll bar to get to the 
  next page.

After a day at the office, you pick up the phone and start dialling 
  an IP number...

You get in the elevator and double-click the button for the floor 
  you want.

Not only do you check your email more often than your paper mail, but 
  you remember your {network address} faster than your postal one.

You look for an icon to double-click to open your bedroom window.

You go to balance your checkbook and discover that you're doing the 
  math in octal.

You look for a trash can icon when throwing out the garbage.