Smoothly animating, very configurable and easy to install. No Ajax, pure Javascript, and without Mootools :).
For those who love this datepicker, like I do, but don't want to be dependent to Mootools library, here I'm "trying" to remove that dependency while adding some features like mouse scrolling and keyboard editing. It requires Hamster JS (https://github.com/monospaced/hamster.js) for scrolling and Anim JS (https://github.com/relay/anim) for little animation.
For usage, you can read at http://www.monkeyphysics.com/mootools/script/2/datepicker
Big thanks to MonkeyPhysics for the great datepicker.
NOTE: There might be bugs since I haven't tested everything yet, besides I'm a novice to Javascript.