Krodal:
Are you sure ?
In my opinion the analog inputs do also have the internal pull-up resistors.
You are right, Analog Pins have PULL-UP resistors too.
from http://arduino.cc/en/Tutorial/DigitalPins
Digital Pins
The pins on the Arduino can be configured as either inputs or outputs. This document explains the functioning of the pins in those modes. While the title of this document refers to digital pins, it is important to note that vast majority of Arduino (Atmega) analog pins, may be configured, and used, in exactly the same manner as digital pins.
Sorry my mistake.