Online random number generator

For everyone out there who needs a random number generator for scientific applications but find that the built-in rand() function does not give satisfying results, I made a website that provides random data with good quality: http://makerandomness.appspot.com/. I wanted to make a true random number generator for a long time, but finding a good source of random noise sample is hard. Some implementations exploit the avalanche breakdown current in Zener diodes, others measure some form of quantum mechanical phenomena. Due to cost considerations, I have to use a hosted server like Google App Engine. This precludes the any possibility of making a custom hardware random number generator. But still I found a random source easily obtainable from the Web: Crypto coin hashes! This online random number generator uses hashes generated by crypto-currency networks as building blocks for the random data. If you haven’t heard of cryptocoin mining, it is basically a process of brute-forcing a mathematical puzzle. There are many possible solutions to this puzzle, but only the first one found gets accepted. Which answer is found first depends on lots of factors, and can be considered largely random. For Bitcoin, on average every 10 minutes a solution will be found, giving around 240 bits of random data. That’s not a very high rate, but by combining outputs from all virtual currencies, whose number have burgeoned lately, one could get a pretty significant stream of high quality random bits. Suggestions are welcome.