Are you a writer with Hemingway aspirations? Wouldn’t it be fantastic if, every time you hit a key, you heard the sound of a typewriter hammer striking the paper, just like the great yet doomed man did?
OS X has it covered. Just open System Preferences, and select the Accessibility icon. In the icon list on the left select Keyboard, then put a check alongside Enable Slow Keys. Finally, click the Options button and in the dialog box that appears drag the slider all the way to the left, and also put a check alongside Use Click Key Sounds.
Then start a new document and write that novel you know is inside you.
(To deactivate the typewriter sounds, repeat the steps but uncheck Enable Slow Keys.)