TypeIt4Me is a text-expansion and autocorrection utility, an app that can save you tons of time (and wrist strain) by automatically expanding frequently used words, phrases, and even images with just a few quick keystrokes.
Users have several good apps to choose from in this category, and TypeIt4Me is one of the best and longest-lived (with a successful track record that stretches past two decades). As with similar apps, you just type in a few letters to access your "clippings"--or you can even choose an abbreviation from TypeIt4Me in the menubar. You can set abbreviations to work system-wide or just in specific applications, and an AutoCue feature lets you use clippings with variable data (for example, a commonly typed sentence but with an embedded number that you can change on the fly). TypeIt4Me also gives you a fairly reliable AutoCorrect (using your Mac's spell checker), and you can easily define corrections for your most frequent errors.
TypeIt4Me still lacks some capabilities we'd like to see (such as easier, integrated syncing among machines), but overall it has an extremely useful and flexible feature set and--important for a pervasive app like this--proven stability.