OpenSimplexNoise is a noise algorithm similar to perlin noise and simplex noise. The big plus however is that its not patentet but released into the public domain.
This project tries to implement the reference implementation (wich is in java) in D. Currently, this is in development.
Credit to the creator(s) of this algorithm: http://uniblock.tumblr.com/ and the reference implementation https://gist.github.com/KdotJPG/b1270127455a94ac5d19
See the LICENCE file. The algorithm is public domain, this code is MIT Licenced.