CTO, Technical Lead, Software Engineer, Indie Hacker, Gamer
Update (05/08/2010): Updated for Magento 18.104.22.168
Magento uses a fantastic event hooking system, following the well known Observer Design Pattern, allowing additional functionality to be plugged in and out without modifying the core code.
It can be difficult to know the names of the various hooks used all over the code base and even more difficult to find where they are used. It is for this reason I have produced a Magento Events Cheat Sheet which will be updated with each new Magento release.