Mac OS X | How to Search the Mac App Store for Apps to Open a Specific File Extension

Step One
Launch the Mac App Store by clicking its icon in your dock. If you do not have the Mac App Store installed then you will need to upgrade your OS to Snow Leopard 10.6.6.


Step Two
In the search field at the top right of the window input extension: followed by the file extension you would like to search for and press Enter. ie. "extension:psd"


Step Three
iTunes will now display a list of applications that are capable of opening that extension.


[via LifeHacker]