The AWSOM Drop Down Archive is a plugin that displays a drop down archive of your posts above your posts on your index and individual posts page. Users can simply select a post from the list and they will immediately be sent to that post. The plugin requires no editing to your theme files to work, simply put in your wp-content/plugins folder and activate it in the Admin Plugins area to make the archive appear.

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AWSOM Drop Down Archive Plugin, WordPress, Plugins, WordPress Plugin