Code:
#!/usr/bin/python

"""
gencc: A simple program to generate credit card numbers that pass the MOD 10 check
(Luhn formula).
"""

from random import Random
import sys
import copy

visaPrefixList = [ 	['4', '5', '3', '9'], 
	            	['4', '5', '5', '6'], 
               		['4', '9', '1', '6'],
                    ['4', '5', '3', '2'], 
             	    ['4', '9', '2', '9'],
                    ['4', '0', '2', '4', '0', '0', '7', '1'],
                    ['4', '4', '8', '6'],
                    ['4', '7', '1', '6'],
                    ['4'] ]

mastercardPrefixList = [    ['5', '1'],
                            ['5', '2'],
                            ['5', '3'],
                            ['5', '4'],
                            ['5', '5'] ]

amexPrefixList = [  ['3', '4'],
                    ['3', '7'] ]

discoverPrefixList = [ ['6', '0', '1', '1'] ]

dinersPrefixList = [    ['3', '0', '0'],
                        ['3', '0', '1'],
                        ['3', '0', '2'],
                        ['3', '0', '3'],
                        ['3', '6'],
                        ['3', '8'] ]

enRoutePrefixList = [   ['2', '0', '1', '4'],
                        ['2', '1', '4', '9'] ]

jcbPrefixList16 = [   ['3', '0', '8', '8'],
                    ['3', '0', '9', '6'],
                    ['3', '1', '1', '2'],
                    ['3', '1', '5', '8'],
                    ['3', '3', '3', '7'],
                    ['3', '5', '2', '8'] ]

jcbPrefixList15 = [ ['2', '1', '0', '0'],
                    ['1', '8', '0', '0'] ]

voyagerPrefixList = [ ['8', '6', '9', '9'] ]                    
                    

"""
'prefix' is the start of the CC number as a string, any number of digits.
'length' is the length of the CC number to generate. Typically 13 or 16
"""
def completed_number(prefix, length):

    ccnumber = prefix

    # generate digits

    while len(ccnumber) < (length - 1):
    	digit = generator.choice(['0',  '1', '2', '3', '4', '5', '6', '7', '8', '9'])
    	ccnumber.append(digit)


    # Calculate sum 

    sum = 0
    pos = 0

    reversedCCnumber = []
    reversedCCnumber.extend(ccnumber)
    reversedCCnumber.reverse()

    while pos < length - 1:

        odd = int( reversedCCnumber[pos] ) * 2
        if odd > 9:
            odd -= 9

        sum += odd

        if pos != (length - 2):

            sum += int( reversedCCnumber[pos+1] )

        pos += 2

    # Calculate check digit

    checkdigit = ((sum / 10 + 1) * 10 - sum) % 10

    ccnumber.append( str(checkdigit) )
    
    return ''.join(ccnumber)

def credit_card_number(generator, prefixList, length, howMany):

    result = []

    for i in range(howMany):
   
        ccnumber = copy.copy( generator.choice(prefixList) )

        result.append( completed_number(ccnumber, length) )

    return result

def output(title, numbers):

    result = []
    result.append(title)
    result.append( '-' * len(title) )
    result.append( '\n'.join(numbers) )
    result.append( '' )

    return '\n'.join(result)

#
# Main
#

generator = Random()
generator.seed()        # Seed from current time

print "darkcoding credit card generator "
print

mastercard = credit_card_number(generator, mastercardPrefixList, 16, 10)
print output("Mastercard", mastercard)

visa16 = credit_card_number(generator, visaPrefixList, 16, 10)
print output("VISA 16 digit", visa16)

visa13 = credit_card_number(generator, visaPrefixList, 13, 5)
print output("VISA 13 digit", visa13)

amex = credit_card_number(generator, amexPrefixList, 15, 5)
print output("American Express", amex)

# Minor cards

discover = credit_card_number(generator, discoverPrefixList, 16, 3)
print output("Discover", discover)

diners = credit_card_number(generator, dinersPrefixList, 14, 3)
print output("Diners Club / Carte Blanche", diners)

enRoute = credit_card_number(generator, enRoutePrefixList, 15, 3)
print output("enRoute", enRoute)

jcb15 = credit_card_number(generator, jcbPrefixList15, 15, 3)
print output("JCB 15 digit", jcb15)

jcb16 = credit_card_number(generator, jcbPrefixList16, 16, 3)
print output("JCB 16 digit", jcb16)

voyager = credit_card_number(generator, voyagerPrefixList, 15, 3)
print output("Voyager", voyager)