It was a good week for Prototype lovers! Right along the Prototype 1.6 security and performance release, Kangax (a very active community member) released an awesome, full-page, beautiful Prototype cheatsheet covering the very same release.
In the bottom corner there is an incredibly useful diagram for those not yet familiar with dimensions/offsets API of elements and viewport. So, download the Prototype cheatsheet, print it, hang it on your wall. I know I will.