Flexi Content has started something that should have been in the core a long time ago. The integration of various plugins. They have taken a stance to get as many extensions to work with their cck and the advantage - you don't invent another k2 or zoo and then a family of extensions that only work with those ccks. Drupal scores over joomla in this issue which has a native cck. The closest thing to a core cck, (i.e. compatibility with all other extensions,ability to create forms, add fields, change the article structure and have own templates) on JED are SEBLOD & FlexiContent. Flexi content is beautifully designed and simple,unlike SEBLOD you understand the system almost intuitively. I pity the people who run the support form for they have to take up issues related to every other plugin in the JED. The templating system requires a special mention. I applaud the effort put in by the team to design such a cool CCK.