I recently stumbled upon a feature of the Leopard dock I didn’t know existed. You can interactively resize the dock by dragging on the separator, (the dashed area on the dock that separates your applications from your folders) with your mouse. Make sure you drag vertically (up and down) not right and left. This is handy when you have so many running applications that the dock is covering up the desktop in undesired ways, as in the picture below which shows the clock getting covered up.
One other way to change the dock features, without going into preferences, is to right-click the separator (control+click for the one button mouse users) which will reveal a context menu of choices for the dock as shown below. This is a quick and easy way to turn dock hiding on and off.