A relatively new feature of Joomla! is the ability to display the same module in multiple positions, and varying it depending on which page you are looking at. For example, you might want to display the search module in the header position on home page, but you want it in the left position on each sub page. Here is a quick and easy way to accomplish this.
Step 1: Make a Copy of Your Module
For this example, I will be working with the "Search" module. Joomla! makes it easy to make a copy of each module. Just follow these steps:
1) Select the checkbox of the module you wish to copy in your module manager.
2) Click the "Copy" button in the toolbar.
3) Voila! You have copied your module!
You should now have a "Copy of Search" module listed in your module manager.
Step 2: Modify the Settings for Your Module Copy
Click on "Copy of Search" to modify its settings. The first thing you want to modify is the module position. In this case, our copy needs to go in the left module position.
The next thing we want to modify is the Menu Items for which our module will display. For this example, we want to display our copy in all pages but the "Home" page. To do this, select every menu item in the "Menu Items" except for the "Home" menu item. NOTE: Do not select "All" from the list, as this will cause the copy to display on every page, including the "Home" page.
Step 3: Modify the Settings for Your Original Module
This step is exactly the same as step 2 with a couple of exceptions. For this example, we want our original module to display only on the "Home" page in the "header" position. For this, you need to set the module position to "header", and only select the "Home" menu item in the "Menu Items" list.
You can modify this process to display the same module in as many positions as you want on as many pages as you want. It is strictly up to you. If you have any questions, please post them in the comments.