SMARTReporter is an application that can warn you of some hard disk drive failures before they actually happen!, for example, your Mac has dropped, it can make disk failure even Sudden Motion Sensor are activated. It does so by periodically polling the S.M.A.R.T. status of your hard disk drive. S.M.A.R.T. (Self-Monitoring Analysis and Reporting Technology) is a technology built into most modern hard disk drives that acts as an “early warning system” for pending hard disk drive problems. SMARTReporter can notify you of impending hard disk drive failures by sending e-mails, displaying a warning dialog or executing an application. The current status of your hard disk drives is always displayed.
SMARTReporter relies on the S.M.A.R.T implementation of Mac OS X, it only supports ATA. SATA, eSATA hard disk drives. Currently SMARTReporter does not support SCSI, SAS, or Firewire external hard drives. Please note that a S.M.A.R.T alert doesn’t mean that your hard drives will completely fail for sure, S.M.A.R.T just catch all possible hard drives error, this application just a very valuable disk indicator. It can tell you before your disk become fail :P
You can follow this link for more information about S.M.A.R.T technology.