This article is really interesting.
From the article:
The quantum noise in a laser beam has been used to generate random numbers at the rate of 300 Mbits per second, breaking a record that stood for just a few days.Random numbers are useful beasts, in particular for cryptographers who use them to generate their codes.But how best to make random numbers at useful speeds? The question is intimately linked to the nature of randomness. One way is to rely on a computer to do the task using an algorithm that generates numbers that look and feel random. For example, the digits of pi appear random but can be generated by a simple algorithm. [...]