JoomSEF is a popular component improving Joomla SEO (search engine optimization): rewrites original Joomla URLs to be search engine friendly (SEF) and human understable and also improves your overall Joomla site SEO rating.
* generate SEF URLs
* advanced SEF URL management
* generate and manage metadata (component - based)
* can override default metadada generated by component or Joomla (title, meta tags)
* keywords management
* duplicates management
* 3rd level domain support
* support for other components through extension modules; each component extenstion has own configurable parameters
* multilinguality support (JoomFish) and URL localization
* UTF-8 URLs support
* URL caching
* URL source tracing to help allocate problematic code
* 301 Redirections management
* 404 Page Not Found customization
* online upgrades and extension installations
Support for many Joomla components: AdsManager, AlphaContent, Contacts XTD, Community Builder, Datso Gallery, DocMan, EZ Realty, Fireboard forum, Glossary, iJoomla Components, JE Comparison Charts, JEvents, Jomres, Joomlaboard, JoomFish, Joomla Tags, Jomres (Joomla Residents), Portfol, Seyret Video Component, SMF Bridge, SOBI2, Marketplace, Mosets Hot Property, Mosets Tree, ReMOSitory, RSGallery2, VirtueMart, Zoom Media Gallery. ...
at the moment, there is more than 100 extensions available directly from ARTIO - see http://www.artio.net/en/joomsef/artio-joomsef-extensions for complete list, plus many more from 3rd party developers.