This is my transfer of popular brush pack from zbrush to blender. I did not make alphas on my own, but author gave all his brushes for free so, I guess, I could take them and use in blender :) I tried to emulate this brushes as close as they work in zbrush.
This brushes was created by 3D Senior Environment Artist at Blizzard Entertainment (Michael Vicente aka ORB) If you really like them, you can purchase pack for any price you wish here: https://gumroad.com/l/nOkHw
p.s. If you have better solutions for parameters, let me know, I'll update this pack.
Tutorial on how to install brushes once and forever http://i.imgur.com/x4YrvbN.png