If you don't want to build your own generator, random.org provides a service like the ANU Quantum Random Number Server, i.e. provision of unique sets of true random numbers by http request, but generated from atmospheric noise. There's a convenience R package "random" I often use for this purpose. The articles on the website are quite edifying regarding the art and science of random numbers generally. Here's a link to the interface documentation: http://www.random.org/clients/http/