Iam Haigh has created an AE script and Hi. I'm proud to announce Ease and Wizz! It's an After Effects script and a whole bunch of expressions - "the fruit of many, many hours trying to figure out how adapt Robert Penner's Flash-based easing equations to work as expressions in After Effects."
Ease and Wizz lets you use several kinds of easing (rather than just
"easy-ease") in a handy way: Expo, Circ, Quint, Quart, Quad, Sine
He also has included "Special effects" eases: Back, Bounce, Elastic
You can see the different types of easing here or in this really basic video that Ian made a while back.
You can download Ease and Wizz here. Ian explains that there are some rough edges, but he has been using it in a production environment for some time and have been pleased with it.
I welcome your feedback, and hope that you find it useful!