as for this question, I'd like to share with you guys this online barcode generator

I have used this free trial ISBN barcode generator. You can find sample code to create the barcode there. Here is the sample code:
using System;
using System.Collections.Generic;
using System.Text;
using OnBarcode.Barcode;
using System.Drawing.Imaging;
using System.Drawing;

Linear barcode = new Linear();

// ISBN Barcode Basic Settings
barcode.Type = BarcodeType.ISBN;

/*
ISBN Valid data char set:
0, 1, 2, 3, 4, 5, 6, 7, 8, 9 (Digits)

ISBN Valid data length: 12 digits only, starting with "978" or "979" only
*/
barcode.Data = "978730216365";

// for ISBN with supplement data (2 or 5 digits)
/*
barcode.SupData = "12";
// supplement bar height vs bar height ratio
barcode.SupHeight = 0.8f;
// space between barcode and supplement barcode (in pixel)
barcode.SupSpace = 15;
*/

// Barcode Size Related Settings
barcode.UOM = UnitOfMeasure.PIXEL;
barcode.X = 1;
barcode.Y = 80;
barcode.LeftMargin = 20;
barcode.RightMargin = 20;
barcode.TopMargin = 0;
barcode.BottomMargin = 0;
barcode.Resolution = 96;
barcode.Rotate = Rotate.Rotate0;

// Barcode Text Settings
barcode.ShowText = true;
barcode.TextFont = new Font("Arial", 9f, FontStyle.Regular);
barcode.TextMargin = 6;

// Image format setting
barcode.Format = System.Drawing.Imaging.ImageFormat.Gif;

barcode.drawBarcode("c:\isbn.gif");
For more info, you can read this barcode creation guide.

here is a tutorial about how to generate ISBN barcodes. i'd like to share with you. take a look at the barcode maker.

in which platform you wanna generate ISBN barcode in ? well,i've ever used ISBN barcode generator in vb.net demo code ,you may have a look
and besides,

I have only tried to generate ISBN barcode using VB.NET before. And npw I am looking for a fine tool to help me deal with reading ISBN barcode using C#.NET. Any help will be appreciated. Thanks in advance.

Best regards,
Aroon

or you may check this ISBN barcode in winformsor another example about ISBN in crystal report

Check following post on C# barcode generation

http://stackoverflow.com/questions/2093368/php-barcode-image-generator

According to that you work in book design,you may use isbn barcode generator to generate isbn barcode.
Here is a simple PHP script for generating barocdes:

<?php
//For displaying barcodes

//Arguments are:
//  code    Number you want outputted as a barcode

//You can use this script in two ways:
//  From a webpage/PHP script   <img src='/images/barcode.php?code=12345'/>
//  Directly in your web browser    http://www.example.com/images/barcode.php?code=12345

//Outputs the code as a barcode, surrounded by an asterisk (as per standard)
//Will only output numbers, text will appear as gaps
//Image width is dynamic, depending on how much data there is

//Get the barcode font (called 'free3of9') from here http://www.barcodesinc.com/free-barcode-font/

header("Content-type: image/png");
$file = "images/barcode.png"; // path to base png image
$im = imagecreatefrompng($file); // open the blank image
$string = $_GET['code']; // get the code from URL
imagealphablending($im, true); // set alpha blending on
imagesavealpha($im, true); // save alphablending setting (important)

$black = imagecolorallocate($im, 0, 0, 0); // colour of barcode

$font_height=40; // barcode font size. anything smaller and it will appear jumbled and will not be able to be read by scanners

$newwidth=((strlen($string)*20)+41); // allocate width of barcode. each character is 20px across, plus add in the asterisk's
$thumb = imagecreatetruecolor($newwidth, 40); // generate a new image with correct dimensions

imagecopyresized($thumb, $im, 0, 0, 0, 0, $newwidth, 40, 10, 10); // copy image to thumb
imagettftext($thumb, $font_height, 0, 1, 40, $black, 'c:windowsfontsfree3of9.ttf', '*'.$string.'*'); // add text to image

//show the image
imagepng($thumb);
imagedestroy($thumb);
?>