Themes Macro and themes action
The Themes package has an action which allows one to call a page and specify what theme should be used to display the page. There is also a macro which can generate links with the action argument, so that one can try displaying a page with different themes.
Syntax/usage:
[[Themes]]
To call a page with a particular theme use:
http://www.pangloss.com/wiki/ChrisSeidel?action=theme&theme=plsavez