I was developing an application recently that needed some king of horizontal bars to be drawn on a web page. I found the jQuery Progressbar plugin and found it it was something similar to what I wanted to achieve, so I took some spare time and modified it to convert it in a plugin I could use in my app. The result is the jQuery Bars plugin. It's a pretty simple plugin that will take a div and convert it into a horizontal bar, in which you can change the background color, the actual bar color, the duration of the animation and the height and width of the bar.
You can check a how it works and looks in this simple test I uploaded. It can be useful if you ever have to shown some kind of a percentage bar in a chart and you need a bit more customization that jQuery UI Progressbar gives you.
The plugin is dual licensed in MIT and GPLv2, the same license as jQuery, so feel free to use it or modify it at your will.