This is a simple plugin that uses wordpress' hierarchy to determine what theme file the current page used to render it!
Use this plugin for all my WP sites. Makes development very easy for figuring out the current file. Plugin does exactly what it says it does.
This plugin does what other "What File?" plugins don't do, which is show the correct template/theme file. Would give 5 stars, but the output is on top of the page header, and could be in the WP toolbar.