This handy little rounded corner generator gives you the html/css and lets you choose a class to name it.
CSS only DOM tabs
Create content changing DOM tabs using only CSS and pseudo-anchors. More light-weight and user-friendly.
Auto-Playing Featured Content Slider

An alteration of the popular “Coda Slider” to incorporate custom thumbnails and auto-playing.
add onfocus functionality to input fields
The focus behavior of form elements is not supported correctly in all browsers. That’s why I created this simple small script to add this functionality to all text fields in a page. It uses the YUI javascript library, but it off course can be made also for other libraries like jQuery or Prototype.
GlassBox – Better UI

GlassBox is a compact Javascript User Interface (UI) library, which use Prototype and Script.aculo.us for some effects. With GlassBox you can build transparent border, colorful layouts and “Flash-like” effects. The GlassBox library .. * is easy to use * is customizable and skinnable * comes with a coherent API (CSS based parameter) and a short [...]
Spice up your images with this script!

instant.js 2.0 allows you to add an instant picture effect (including tilt) to images on your webpages (alternatively: slided.js or filmed.js). It works in all the major browsers – Mozilla Firefox 1.5+, Opera 9+, Safari and IE6+. On older browsers, it’ll degrade and your visitors won’t notice a thing.
MooFlow

Another great gallery/slider built upon Moo Tools. It’s slightly buggy with large file sizes, but can handle quite a large quantity of images.
ImageFlow 0.9

Image flow is a very smooth and very fast slider that doesn’t require a heavy framework to operate.
Live Pipe – Extensions for Prototype
LivePipe UI is a suite of high quality widgets and controls for web 2.0 applications built using the Prototype JavaScript Framework. Each control is well tested, highly extensible, fully documented and degrades gracefully for non JavaScript enabled browsers where possible. MIT licensed and actively maintained.
Fading JavaScript Tooltips

This animated JavaScript tooltip script is very easy to use and lightweight at only 2kb. It is tested working in IE6+, Firefox, Opera and Safari.
Dynamic Image Gallery & Slideshow

An extremely lightweight image gallery & slideshow.
EO Gallery-Jquery

EOGallery is a web animated slideshow gallery maid with jQuery.

