David Richardson has created a multiple-part tutorial for modeling a mech in ZBrush.
Art for Games - Memory Folds in Clothing Tutorial
Art for Games have posted a free tutorial on creating memory folds in cloth, using ZBrush and Photosohp.
MatCap Materials Pack
Adam Lewis has donated a MatCap materials pack containing 36 materials for ZBrush.
Ruan Ji - ZBrush Art
Check out some amazing modeling and texturing by ZBrush artist Ruan Ji.