I have made a couple of apps that require credit cards numbers.  To save time and hits to your merchant account, it is a good idea to validate the user credit card number BEFORE sending to your authorization service.  Below is a list of some common credit card carriers and some test credit card numbers.  These credit card numbers can be used to validate your credit card validation algorithm.  

Credit Card Type - Credit Card Number

• American Express – 378282246310005
• American Express – 371449635398431
• American Express Corporate - 378734493671000
• Australian BankCard - 5610591081018250
• Diners Club - 30569309025904
• Diners Club - 38520000023237
• Discover - 6011111111111117
• Discover - 6011000990139424
• JCB - 3530111333300000
• JCB - 3566002020360505
• MasterCard - 5555555555554444
• MasterCard - 5105105105105100
• Visa - 4111111111111111
• Visa - 4012888888881881
• Visa - 4222222222222

I would like to thank PayPalObjects.com for this great information.  For a more detailed list, please visit the PayPalObject’s page.

Just found another cool link that generates a random credit card number: http://mediakey.dk/~cc/wp-dyn/credit-card-number-generator.php I hope my card number doesn’t turn up!