Accordion is a UI pattern made up of a series of containers for your content, all of which are closed when the new panel opens and reveals itself. Chris Coyier came up with Grid Accordion (powered by jQuery and CSS). It works with the same theory as most other accordions. Only one cell is opened at a time. The big thing is that the column of the current open cell expands to a reasonable reading width. The effect is really awesome as it offers you a handy alternative to classical accordions, by adding all the data you need in a single table.
One way to look at an accordion is like a collapsed single column of a table. I was recently building a page for a client site, where the information that they provided really made sense to present as a table. But it was too much information to view all at once. I thought it would have been overwhelming visually. I also thought that it was most likely that people visiting this page would know what they needed right away, so having them click once to get it seemed pretty reasonable. So, a table of accordions!