ANOTHER CHEAP EXTERNAL HARD DRIVE. Back up, people. One of my students had to make an emergency run to the Apple Store to get her paper off the hard drive of a suddenly-dead MacBook. Get an external drive, or — if you’re working on a single important document like a paper — just email yourself a copy as a backup using gmail or hotmail or some web-based service that keeps a copy on the server. Otherwise, you’re cruising for trouble.