Quantifying randomness
You can use some mapping to convert strings to numeric and then apply standard tests like Diehard and TestU01. Note that long sequences of samples are needed (typically few MB files will do)
I've come up with 2 methods to generate relatively short random strings- one is much faster and simpler and the other much slower but I think more random.  Is there a not-super-complicated method or way to measure how random the data from each method might be?
I've tried compressing the output strings (via zlib) figuring the more truly random the data, the less it will compress but that hasn't proved much.