Things happen - power spikes, magnetic fields, just about anything and poof - your data is gone or worse - your machine no longer functions! I am the Mac support person where I work and rarely run into major problems, but when I am stumped, I am so glad I can call AppleCare.

The folks who answer the phone are never in a hurry - they are patient, friendly and sympathetic. They will spend hours if needed, in helping you diagnose the cause of a problem you're having and if needed, they will give you a case number and refer you to an Apple-authorized repair center that will make the repairs at Apple's expense. Naturally, this is not like homeowners insurance - the warranty won't cover things like flood or fire, but if something suddenly stops working or is behaving weirdly, this is what you need.

Without fail, every AppleCare warranty I've ever bought has paid for itself several times over. Never buy a new Mac without one!