Michael Pavlovich's Zbrush tutorials:
Shane Olson's brushes and interface: Nice workflow and brushes, inexpensive. https://gumroad.com/shaneolson
MAHcut_Mech_A: Great for creases.
In case not available at the above link.
SK_Trim_Polish: Good for polishing, a few other good brushes here.
Multiple SK brushes
Or if you prefer the single brush, here's a direct link.
SK_Polish: Basically a gentler version of the above brush that biases toward creating edges rather than trimming them.
ORB Brushes: Good for Blizzard-style sculpts
Selwy's Cloth Brushes
Ornament brush alphas:
Lots of tech kit-bash brushes: