http://www.reallusion.com/creative/ Genetica is a powerful node-based texture generator perfect for tiling, creating seamless textures, adding weather effect...
Remember, today is last day for the 50 % off for reg. iClone users for this great tool. It should have free update to next version included. Read about here. It is the best you can get in my opinion - it is expensive but 50% off help a lot.
Remember that Genetica is a stand alone program who can be used by every one and with any other software. @safegaard
Via Henrik Safegaard - Cloneartist