You can use the ADC as a random source, as dannyf says, but no matter what, the entropy generated from sampling the ADC will have bias. Thus it's not truly random, and will fail tests for randomness, such as the Diehard tests, as Kjelt says. It can likely be used as is for games, blinky lights and what not.
The random sampled data from the ADC can be whitened with a small LFSR, a TGFSR, a huffman compression, a CRC calculation, or a pass through a
tiny Mersenne twister. In a much more simpler way, suitable for a small micro in software, you can examine the bits two at a time and output 1 bit ala Von Neumann: "1,0" -> 1 , "0,1" -> 0 , ("00"|"11")->discard. You can also take the sampled output from two ADCs and XOR them together to get 1 bit stream.
Any of those methods would make it statistically more random, but not necessarily cryptographically random. Clearly Stonent doesn't need cryptographic randomness