More Fields is part of a suite of plugins created to enhance the functionality of a vanilla WordPress installation. With <a href="http://wordpress.org/extend/plugins/more-types/">More Types</a> you can create additional post types besides Pages and Posts, with <a href="http://wordpress.org/extend/plugins/more-taxonomies/">More Taxonomies</a> you can create additional taxonomies besides Categories and Tags. More Fields works without the other plugins but interacts with them nicely.