while I don't have pics readily available, the finishes that come to mind are:
Cerrakote (cerakote?)
Cold bluing
Forced Patina (mustard, vinegar, bleach/steel wool, etc etc)
Powder Coat
Parkerizing
Those are all "coating" finishes. As far as actual metal finishing:
mirror buff
vertical 'brushed'
horizontal 'brushed'
hand rubbed satin
media blasted (different media types would of course produce different results, most common is shot peening and glass bead for unique finishes)
Thats all I can think of right off the top of my head.