The hottest new extension in Joomla is K2.
Why? Normal Joomla articles provide you with a Title and Body. K2 gives you the flexibility to add much more information. For example, this is part of a K2 article about a camera called the Canon EOS Rebel:

Beyond just an article, you can add information about:
- Price
- Weight
- Color
- A link for more information
You can also add tags, videos, photo galleries, comments and more. You can see the full Canon EOS Rebel example article here.
That is the essential benefit of K2 ... you can create articles with far more information and features.