A couple of weeks ago, the driver side window started squeaking and chirping whenever I raised or lowered it. I took off the door panel and found that the regulator pulleys, at the bottom of the door, were the culprit. I oiled the pulleys, greased the cables and the rails and everything was fine.
Then, I realized that I probably could have done all of this without even removing the door panel. At the bottom of the door, there are four plugs which give access to the adjusting bolts for the window regulator. With the plugs removed, you can get access to the pulleys and the window rails for lubrication. I lubed the passenger door window regulator in about five minutes.