Upon a suggestion in another thread I have taken a look at Genetica by Spiral Graphics and must say that it is amazing. In the beginning it´s a bit hard to wrap your head around some key concepts but once you are there a texture like the one below is done in 5 minutes. Try it in PS. Right now they have a discount of 40% because the new version 4 is comming up. So anyone interessted can download a trial version for 30 days and take a look.