Borrowing yet another feature from iOS, Mavericks now supports text-substitution shortcuts. For example, you can configure your system so that anytime you type "teh", it will replace it with "the". You can also create your own custom substitutions, such as "OMW" for "On my way," or whatever else you can think of.
You can enable this feature by going to System Preferences and then going to the Keyboard utility. Once there, go to “Text”. Next, hit “Add” whereupon you’ll be prompted to type in the text to be replaced along with its replacement. You can also customize which apps will incorporate your text substitution changes.