A tiny menu bar utility, Caffeine prevents your Mac from activating the screen saver or sleeping when idle. Presenting as a cup of coffee, the icon indicates whether Caffeine is active, denoted by a full cup of coffee, or inactive, when the coffee cup is empty.
Caffeine is activated by clicking on the menu bar icon. You can define a set period of activity from five minutes to five hours, or set it to be active indefinitely via a right-click or in the settings.
While you can replicate the features of Caffeine using System Preferences, having a quick and easy sleep preventer in your menu bar is a real boon. It's cute, effective, and best of all, Caffeine is absolutely free. Grab it now from the Mac App Store.