Gerber has produced a number of smaller pocket/keychain sized multi-tools. Here are a few photos showing you a size and tool comparison between them. Gerber, being owned by Fiskars, tends to love scissor based multi-tools...something I am all for. Therefore, there have been a few sets of multi-tools that get produced at the same time. One based around pliers, the other around scissors.
The Gerber Clutch (pliers), and Shortcut (scissors), and the Gerber Vise (pliers), and Splice (scissors) come to mind as such a pair.
Something that I should also add, most of Gerber's little multi-tools tend to have spring related issues. Lots of these little guys have such strong back-springs, that they will break a nail on you if your not careful. On the plus side, snap one of these closed for an impressive sound and action. Some of these spring closed like a mouse trap. This adds to the fiddle factor in spades.
Then you have the older designs, most of them based on scissors such as the Eclipse and Solstice.
Because of size, I also threw in the cute and capable Curve. No pliers on this model, but it has a lot of functionality in a small package.