wpquestions.com, ID = 3810

/**
 * Add additional custom fields to profile page
 */

add_action ( 'show_user_profile', 'wpq_show_extra_profile_fields' );
add_action ( 'edit_user_profile', 'wpq_show_extra_profile_fields' );

function wpq_show_extra_profile_fields ( $user ) {
?>

    <h3><?php _e( 'Extra Profile Info'); ?></h3>

    <table class="form-table">

        <?php // duplicate this chunk (changing the meta field) for more fields ?>
        <tr>

            <th><label for="icl_admin_language"><?php _e( 'Admin Language' ); ?></label></th>

            <td>
                <?php $value = get_the_author_meta( 'icl_admin_language', $user->ID ); ?>
                <select name="icl_admin_language" id="icl_admin_language">
                    <option value="en" <?php selected( $value, 'en' ); ?>>English</option>
                    <option value="es" <?php selected( $value, 'es' ); ?>>Espanol</option>
                    <option value="it" <?php selected( $value, 'it' ); ?>>Italiano</option>
                </select>
            </td>

        </tr>
        <?php // end of chunk ?>

    </table>

<?php
}

/**
 * Save data input from custom field on profile page
 */

add_action ( 'personal_options_update', 'wpq_save_extra_profile_fields' );
add_action ( 'edit_user_profile_update', 'wpq_save_extra_profile_fields' );

function wpq_save_extra_profile_fields( $user_id ) {

    if ( !current_user_can( 'edit_user', $user_id ) )
        return false;

    // copy this line for other fields
    update_user_meta( $user_id, 'icl_admin_language', $_POST['icl_admin_language'] );

}