|Jumi - Deceptively simple, yet powerful|
With this great power comes great responsibility. To make any use of Jumi you need to be comfortable with writing PHP code and accessing MySQL databases. Joomla does provide some nice classes to make this easier, and the few examples on the site show how this can be done. Once you're comfortable with that, Jumi has the potential to replace many different modules and plugins. In fact, I believe it is possible to write your own page templateing system using Jumi, at least on a page by page basis.
So who is Jumi for? Not for the Joomla beginner who hasn't worked with PHP and MySQL before. But if you're comfortable writing your own code, Jumi lets you pry open Joomla's hood and work directly with the engine, allowing you to make Joomla sing to your own tune. All without hacking any core files.