One of the biggest advantages of Joomla is that there are many open source components that could be used to add any functionality to a website. For example: It can automatically generate Site Map; generate and import RSS; adding comments and many more. Here are some of them:

1. GTranslate is Joomla module that uses Google to translate web sites.
2. Attachments for content articles. This component allows uploading and attaching files to an article. You can limit the people who can upload files.
3. PixSearch displays search results at real time. While you are typing in the search box it sends query and returns the result at the moment of typing. You do not have to hit Enter.
4. Missing Metadata is module that adds a panel listing any published articles that have empty metadescription or metakeys. Metadata is important for SEO.
5. AllVideos Plugin allows easily embedding online streaming videos your website as well as videos uploaded on local server or a remote one. You do not have to write or copy any HTML code. Tags look like this: {youtube}Name{/youtube} or {flv}Name{/flv} or {mp3}Name{/mp3}. It supports any kind of media files.
6. Featured Articles is module which allows you to display your selected article titles, to draw attention to them.
7. Popular of late - Often there is problem with the "Most Read Content". Some articles are located, and everyone click on them and they stay in the "Most Popular" section. In this case the new articles don't appear here. One of the ways to avoid this problem is to show popular news for the last XX days. The "Popular of late" module is based on the original "Popular" module and have an additional parameter - the refresh period.
8. VirtueMart is component used in e-Commerce. It is shopping cart for Joomla! It has Store-Mode and Catalog-Mode. It can handle a lot of categories, products, prders, shopper groups and customers.
9. joomlaXplorer is a file and FTP manager. You can browse directories and files, edit, copy, move, delete, search, upload and download them, create new files and directories and change permissions.
10. SmoothGallery Mambot allows you to add slideshows to your website. It is integrated with UGM (Ultimate Gallery Manager) component. It shows images in lightbox, several galleries on one page, generates thumbnails, creates gallery from a folder and more.
11. Community Builder is component that optimizes the user management system.
12. SOBI 2 is Joomla extension that shows entries by categories. It enables paying via Pay Pal.
13. Expose Flash Gallery is flash-based gallery that shows your pictures. It can automatically start a slideshow, direct link to an image or album. Background and foreground image can be loaded.
14. JCE is a tool that can edit image and media files. It is based on Moxiecode's TinyMCE.
15. Events Calendar shows upcoming events on a calendar. Events can be shown in categories. You can also search events and give event feedback.