jQuery is a JavaScript library that emphasizes interaction between JavaScript and HTML. jQuery is considered quite fast and lightweight and helps designers simplify how they handle HTML documents, events, perform animations and add Ajax interactions to their web pages. I know, I know - snooze. But once you see what you can do with it, jQuery gets a lot more interesting. Here are five popular jQuery plugins that you may have seen around the Web and consider implimenting on your own site:

jQuery Virtual Tour: Plugin that allows designers to add interactivity and transform a panoramic image into a virtual tour, providing much more detail within image galleries. Screenshot below:

jQuery Shoutbox: Provides a chat feature for websites that allows visitors to leave messages without any registration. Shoutbox can be styled with CSS, is easy to set up and an archive is available for download.

jQZoom: A plugin that enables designers to magnify an image - essentially providing an additional window layer for the close up. You can see this feature in action on popular ecommerce sites hosted by Volusion.