True random numbers cannot be generated by a computer, but there are devices that can be connected to a computer that will generate true random numbers. Since not everyone has one of these devices, there are services that make these random numbers available through the internet.
Try [random.org](http://random.org) for random integers, sequences, and strings derived from atmostpheric noise. I have a simple class that uses the new `IDLnetURL` to access the website. It can be used like:
IDL> rnd = obj_new('MGrndRandom')
IDL> result = rnd->getIntegers(5, min=0, max=99, error=error)
IDL> help, error
ERROR LONG = 0
IDL> help, result
RESULT LONG = Array
IDL> print, result
63 63 88 62 53
The class is available in my library ([source](https://github.com/mgalloy/mglib/tree/master/src/analysis/mgrndrandom__define.pro),
The [QRBG](http://random.irb.hr/) (Quantum Random Bit Generator) Service generates the random numbers and transmits them to you. There are command line, C++, and Matlab interfaces, but no IDL interface (yet). The limits are 1 GB per session and a maximum of 10 concurrent connections, but has no hard limit to how many random numbers can be obtained in a given time period.
By the way, the (free) registration for the QRBG Service required solving the world's best [CAPTCHA](http://wikipedia.org/wiki/Captcha):