Multitools are the modern implementation of the Swiss army knife. They feature variety of useful tools for mechanics and hobbyists, including knives and screwdrivers, as well as more esoteric features like bottle openers. They are usually built around a central, larger tool, often a pair of pliers, which folds into a small rectangular shape that can easily be kept in a pocket or on a belt. The various blades and other accesories are hidden within the handles and accessed in a similar manner to a jack knife.
While not a replacement for a real set of tools, a multitool is extremely useful if in emergency situations or when the proper tool is not available, and could be considered an indispensable tool to keep with your DeLorean.