Tutorial : Collapsible Menus using jQuery

jQuery has surely made my life easier. I have been trying out both Prototype & jQuery for a couple of days now and for some reason, I find jQuery a lil easier compared to Prototype Javascript Library. Although Prototype is a much powerful library (according to me), jQuery is just too simple . Anyways I will show you a simple effect which you already must have seen in many places.

Demo : The Category section in the sidebar in this site.

EDIT : Added Collapse All, Expand All Code as well