Joomla allows you to assign modules to pages that are linked to a menu. Unfortunately, you can not assign a module to a page that is not linked to a menu. For example, you can link to a section or category and when you click that link, it will display links to all articles in the Section or Category. Unfortunately, you can not assign a module to the articles that are listed for a Section or Category. The only way to get a module to appear on these articles is to link those articles directly to the menu or to assign the module to ALL pages. But neither of these solutions is practical if you want to automatically list all articles in a Section or Category. MetaMod to the rescue.
MetaMod is a highly configurable Joomla module that allows you to create very specific rules for displaying modules. In the scenario above, I was able to specify that if any article from category ID X is displayed, then display X Module.
But this Joomla module does way more than that. It allows you to control Joomla module display by date, time, repeating time, GeoIP (country of viewer), browser type and language, user name, group, page within other component (eg Virtuemart), on-page text, by article keywords , individual article, section / category, and more.
For example, you can use MetaMod to display modules on a schedule; specify a start and stop day and the module will be displayed on that schedule. Or, if you want users from different cities to see different modules, MetaMod can do that too.
And what's more amazing is that this module is free and has great documentation. The only downside to this module is that anything anything more than the basic configuration requires some knowledge of PHP programming. But to help with this, the MetaMod website provides dozens of php recipes that help you understand and implement the recipes for many common module display scenarios.
It's funny how you can develop dozens of Joomla sites without the help of a wonderful Joomla extension like this. Last week I'd never hear of this module. This week I've used it on two sites to solve a Module display problem. A big THANKS to the developers of MetaMod!