Webchunks is a Firefox3 implementation of Microsoft Webslices (feature appeared with IE8). It allows you to “follow” an area of a web page through a dedicated feed bookmarked in a new toolbar. Clicking on the toolbar entry shows the information related to your choice in a popup, without the need to open a complete web page.
Should you follow information that can expire like eBay auctions, the style (bold or italic) of the toolbar’s entry will reflect the status of your entry: new, expired, about to expire. With the help of an extra extension, Greasemonkey, you can insert webchunks/webslices markup into any web page so the Webchunks extension handles it. This is something the Microsoft implementation cannot do, it entirely relies on the server’s markup.