You can transform a uniform distribution into something usable for, say, minecraft-style biome generation, but it's much more involved than just summing up distributions. Look into fractional brownian motion, perlin noise, etc...

The graphs on the page you link are probability distribution functions, which map any output number to its probability of being generated (well, actually, since we're looking at a continuous range of values, it's really the probability of generating an output between some A and B). They don't mean anything else and a normal distribution will still have a large variance.

Fractional brownian motion seems to be the closest thing you are looking for. Basically, it will take a sample of uniformily generated random numbers, and output a sample of "smooth" noise, which when mapped to a heightmap, would give a somewhat realistic terrain instead of a completely random mess. It involves summing up octaves of the same uniform sample, with different frequency and amplitude. Is this what you were looking for?