A simple module to put a background image that fits allways the browser size.
The background image can selected for a menu entry as it is possible with every Joomla! module.
Put either an new module position in your template or use an available the position, like for example "debug".
This module uses MooTools to resize the background image. That means for Joomla! 3, you have to switch "Load mootools" to "Yes". For Joomla! 2.5 it is not necessary.