Using an RTL-SDR as a Cheap Entropy Source
One of the many uses of the RTL-SDR is as a random number generator for generating entropy. Entropy is needed in computing for many application such as in encryption and security.
Noel Bourke has written an article on his blog about using the RTL-SDR as an entropy source on Linux. Noel uses RTL-Entropy and shows how to set up Linux to use the RTL-SDR as the entropy source for /dev/random.