SMG: Lets a character control basic submachine guns like the Uzi or Mac 17. May make a big difference when you're outnumbered three to one by bandits who've decided that they want the gold from your teeth.
SMG is a great step up from Clip Pistol and Rifle for three reasons: magazine size, use of only pistol ammo, and the ability to AUTO and BURST fire. Although this skill will not suffice later on when the fighting gets rough, it's a fun skill to experiment with until an Assault Rifle is available. If not, then at least as a means to gain a small promotion.