Hoststacker includes fine styles for a lot of extensions, like K2 Content, Youdeveloper News Slider, YJ Module Engine, YJ Latest Tweet and YJ Plans Extended. You!Joomla build it on their YjSimpleGrid Framework, which comes with YJSG Template Manager, YJ Mega Menu and 5 pre-defined styles. Hoststacker is ready for Joomla 2.5, Joomla 3.0 and Joomla 3.1. It works also in the former version, Joomla 1.7. The download is commercial. You can use it best for hosting websites.