Simple function that links up your settings page from the plugin overview page:

wp_plugin_settings_link.php

function atfi_settings_link($links, $file) {
    $plugin_file = basename(__FILE__);
    if (basename($file) == $plugin_file) {
        $settings_link = '<a href="options-general.php?page=atfi">Settings</a>';
        array_unshift($links, $settings_link);
    }
    return $links;
}

add_filter('plugin_action_links', 'atfi_settings_link', 10, 2);