You would like to put some Module at your site but don't know where to put it.... Or "Nice site, is it Joomla! ?"... Or "How did they use some area at that Joomla! site? Is it a Module?"... You can easily find out yourself, without being logged in!
Add the parameter ?tp=1 behind the URL, e.g. http://www.joomla.org/?tp=1
The following parameters can be used: 0=normal, 1=horiz, -1=no wrapper.
Technical background: In Joomla 1.0.15 this functionality is called "function mosLoadModules" and can be found in /includes/frontend.php (Joomla 1.0.15: line 122).