Webmoves_DefaultCatView is a Magento extension that allows you to set the default product list type (grid or list) per category.
Out of the box, Magento only allows you to set a default list type for all categories in your store. This module adds an option to the Display Settings for each category that allows you to specify Grid, List, or Default on a per category basis.
To install the module, simply unzip it in the webroot of your Magento installation.