mosheeshel

This plugin extends Theme Switcher and Theme Switcher Reloaded, this plugin detects the existing active plugin and uses it to display a floating list of available themes, to enable creating a Theme demo site.
Basically it enables anyone to create a demo site of all his available themes, just create a site with all the demo pages you can think of. The download and Enable either Theme Switcher or Theme Switcher Reloaded plugins, and this plugin, and when you access any page on the site a floating div will appear on the top left side of the site, showing a dropdown menu wutg the current theme selected. When you choose a different theme from the list, the site will switch to have that theme as the selected site theme.
Note: that this plugin is dependant on either the Theme Switcher or the Theme Switcher Reloaded plugins, and what it does would not be possible without the work done on those plugins.

Floating Theme List

This plugin extends Theme Switcher (/Reloaded), it displays a floating list of available themes, enabling EASY creation of a theme demo site.

John P. Bloch

Create child themes from any non-child theme with the click of a button.
This plugin is multisite compatible; if used on a multisite network, controls for creating child themes will be in the network admin instead of the regular site admin. Pick the parent theme from the dropdown and name name your new child theme. You can also change the author name and select files you want to copy from the parent to the new theme.
Click the button and you’re all set!

Child Themify

Create child themes with the click of a button.

Floating Theme List vs Child Themify