Update 7/6/2010: version 1.4.1 is out!
There are about a dozen other plugins out there that do this already, except most seem to come with an enormous footprint: 10-12k of code, X-number of images, and roughly 1000 options to support every plausible use case. For other minimalists like myself out there, here’s one built off the jQuery UI widget factory in approx. 110 lines of code and 100% CSS. In typical widget fashion, this implementation supports the most basic (and arguably most common) uses, but is flexible enough for more advanced cases.
Internet Explorer is a big-time downer with no HSLA/border-radius/box-shadow support, so if eye candy is important to you in IE, a transparent png background or similar can be added without much effort. (more…)