GreenSock Animation Platform (GSAP)

This is a great tool that I used in my ActionScript projects for years and now there is a javascript version. You can animate any CSS properties of DOM elements which is making HTML development look super slick. GSAP claims to be up to 20 times faster than JQuery and I believe it. For a couple of years now I have been trying to get a friend of mine (he is a HTML Developer) to try GSAP. Finally with reluctance he started using it and his words to me now are "why isn't everyone using it?".

In addition to setting up individual tweens you can also set up timelines where you can add multiple tweens and then control those tweens with play, pause, resume, reverse, restart. Check out the API Doc's

GreenSock has been around since the days of ActionScript 2.0 and followed that with a version for ActionScript 3.0. Now you can tween like a pro in javascript too!