No doubt, Zbrush is th ebest, most natural tool to work with.
http://www.pixologic.com/home.php
http://www.wegame.com/watch/Creating_Sculpted_Prims_in_ZBrush_3_Part_1/
http://www.wegame.com/watch/Creating_Sculpted_Prims_in_ZBrush_3_Part_2
Best of luck,
Ami