Catan Dice is meant to be used with Settlers of Catan, the designer board game by Klaus Teuber. It is also designed to be used with the expansion set, Cities and Knights. Catan Dice uses a true random number generator. Catan Dice also has nothing to do with the Catan Dice Game. There is a very good article about Catan on Wired.com which I have used to "convert" many friends over to designer board games.
Being generally unsatisfied with the randomness of the dice that Settlers of Catan and its expansion, Cities and Knights, come with, I decided to write a dice rolling program that utilizes true randomness. Using a true random number generator to come up with rolls should result in more satisfying die rolls since real dice are biased. For example, in the particular playthrough that spurred me to write this program, 9s appeared with alarming regularity while the similar 5s (probability-wise) were rolled a mere three times. With the Catan Dice program, it is not only possible to get a better statistical distribution, but also track the regularity of rolls. Over the course of the game, the distribution of rolls should resemble a bell curve, since the number 7 and its closest friends are probabilistically more likely to be rolled.
It pulls in numbers from Random.org's generously provided (freely available) API that allows one to request sets of random numbers (and other random data). Random.org is the closest thing to a guarantee of true randomness, using atmospheric noise. There is a fascinating explanation on their website explaining how it works.