I've made a number of them myself. For instance, FitVids. But I've screencasted about that one before. This time, I'm going to pick a couple of jQuery plugins that looked neat to me, but I've never ever used them before. I'm doing that on purpose, so can see the thought process that goes into figuring out how a random jQuery plugin works for the first time.
The first one we pick is a lightbox plugin called Boxer. You know, one of those design patterns where you click a thumbnail of an image and it opens a bigger version of it right on the page and kinda darkens out the background. We get it working pretty darn quickly following the documentation.
The next one we pick is called OWL Carousel. It looks like a pretty darn nice slider, having the two big features that you often don't see in older sliders: touch support and flexibility. We get this one working also by using the documentation but also checking out the provided demos.
This is where we got on that one in just a few minutes: