Allows admin pages containing settings forms to be managed semi-automatically. It lets you define settings pages, sections within those pages and fields within the sections.

settings.php

<?php
// ------------------------------------------------------------------
// Add all your sections, fields and settings during admin_init
// ------------------------------------------------------------------
//
function tp_settings_api_init()
{
	// Add the section to reading settings so we can add our
	// fields to it
	add_settings_section(
		'tp_setting_section',
		__('Example settings section in reading'),
		'tp_setting_section_callback_function',
		'reading'
	);
	// Add the field with the names and function to use for our new
	// settings, put it in our new section
	add_settings_field(
		'tp_setting_name',
		__('Specific pages'),
		'tp_setting_callback_function',
		'reading',
		'tp_setting_section'
	);
	// Register our setting so that $_POST handling is done for us and
	// our callback function just has to echo the <input>
	register_setting( 'reading', 'page_contact' );
	register_setting( 'reading', 'page_testimonials' );
}
add_action( 'admin_init', 'tp_settings_api_init' );



// ------------------------------------------------------------------
// Settings section callback function
// ------------------------------------------------------------------
//
// This function is needed if we added a new section. This function
// will be run at the start of our section
//
function tp_setting_section_callback_function()
{
	echo '<p>'. __('Intro text for our settings section') .'</p>';
}



// ------------------------------------------------------------------
// Callback function for our example setting
// ------------------------------------------------------------------
//
// creates a select page option. Other types are possible ;)
//
function tp_setting_callback_function()
{
	?>
	<ul>
		<li><label for="page_contact"><?php printf( __( 'Contact page: %s' ), wp_dropdown_pages( array( 'name' => 'page_contact', 'echo' => 0, 'show_option_none' => __( '&mdash; Select &mdash;' ), 'option_none_value' => '0', 'selected' => get_option( 'page_contact' ) ) ) ); ?></label></li>
		<li><label for="page_testimonials"><?php printf( __( 'Testimonials page: %s' ), wp_dropdown_pages( array( 'name' => 'page_testimonials', 'echo' => 0, 'show_option_none' => __( '&mdash; Select &mdash;' ), 'option_none_value' => '0', 'selected' => get_option( 'page_testimonials' ) ) ) ); ?></label></li>
	</ul>
	<?php
}