Procedurally generated content is a fairly large movement at this point. The most prominent, recent example is probably Minecraft, which relies heavily upon computer algorithms to generate the world and events in the game. There’s no cubicle farm of artists churning out Minecraft landscapes.
To a large extent, we have Ken Perlin to thank for this. Ken was awarded an Academy Award for the invention of Perlin Noise during the production of the film Tron. His name is now ubiquitous, but unfortunately the algorithm which bears his name is dated. Ken published a paper in 2002 describing the drawbacks of Perlin Noise and introducing a new algorithm. Many references to this algorithm confusingly call it Improved Perlin Noise, but it is actually named Simplex Noise.
It seems many developers start searching for noise functions and don’t know which to use. Thankfully, Simplex Noise is a suitable replacement to Perlin Noise in almost every way: the noise is cleaner, less computationally expensive and easier to implement in hardware (if desired). Unfortunately, with all the confusion on the web it’s hard to find a good implementation and impossible to find documentation.