I've been playing around with this idea this morning, and have a bit of data. The idea is simply to regard the LSB of an ADC conversion as a random value (1 or 0) and generate a sequence of these values to create random numbers. I have no idea how valid such numbers would be, but I did do a number of measurements of two pieces of data related to the sequences:
1) How many 1s vs 0s are generated
2) How often a bit is the opposite of the previous bit
I did a number of tests of 1000 ADC readings, and found that both (1) and (2) were always about 50% +/- a couple of percent. Those seem to be encouraging findings. Now I'd like to generate large numbers of 8 and 16-bit values from these sequences and somehow test to see if they are good random numbers. Anybody know how to do that?