jQuery Cheat Sheet
Released by ColorCharge.com. They’ve also released a version for the iPhone/iPod Touch called jTouch.
Download: jQuery Cheat Sheet (PNG, 364kb)
MooTools Cheat Sheet
Released by Jonathan Snook.
Download: MooTools Cheat Sheet (PNG, 111kb)
Prototype Cheat Sheet
Released by kangax
Download: Prototype Cheat Sheet (PDF, 155kb)
Script.aculo.us Cheat Sheet
Released by Amy Hoy
Download:Script.aculo.us Cheat Sheet (PDF, 80kb)
Yahoo User Interface Library
Released by Yahoo
If you know / have cheat sheets to add in the list, Please don’t hesitate to contact me.