With more and more people watching movies on their wide-screen Macs and Apple TV, it's no secret the computer is starting to move in on traditional DVD, Blu-ray, and other video player territory. If you have a laptop and the right cords, you can even plug your computer into your big-screen TV and enjoy all the glory of the new standalone Hulu for Mac. But while your Mac is great for watching movies, your Mac's sleep feature to save energy has a nasty way of making your screen go dark right in the middle of the show. To keep this from happening, you can go into the preference pane before starting a movie, select Energy Saver, then slide the dial to Never sleep. I admit this isn't a terribly hard process, but I found a download that makes it even easier.
Caffeine is a free download that adds a simple icon on the right side of your menubar. When you click it, Caffeine prevents your Mac from going to sleep while you watch your movie. When your movie is over, simply click it again to return to your normal sleep settings. You also can Command-click the icon to bring up settings to set how long you want Caffeine to keep your Mac awake--anywhere from 5 minutes to indefinitely, but it also has 2-hour and 5-hour options for perfect movie-viewing time.