Backup Software and/or Hardware
Only two kinds of Mac users exist: Those who have lost data and those who are going to. If your work means anything to you, you had better back it up before it’s too late. If you have a spare hard drive, by all means use the cool (and free) Time Machine software that comes with Mac OS X Lion. If you want to create multiple backups to several different devices or types of media (DVD-R, CD-R, tape, and so on), invest in the appropriate hardware and software.