Simplex Noise

Apparently, Ken Perlin fixed a bunch of things that were a bit off about Perlin noise in 2001, while also reducing how expensive the function is to compute. The result is named simplex noise.

Here is a neat paper on the subject.

Here is a guy using it in Java, to do procedural content for a simple game. Lots of other cool little projects on this site too, especially web synths.