Free application HDDScan is a utility that diagnoses your hard drive's ills.
The app allows you to analyze drive temperatures, conduct S.M.A.R.T. tests, export and print reports to document changes in your hard drive's health, and works on ATA, SATA, and SCSI drives and, with limitations, on removable drives such as USB and FireWire.
For example, it takes one click to display and another click to print simple hard disk information including serial, firmware and manufacturer, along with 50 or so additional parameters.
While the app is not perfect -- an update is due out soon -- it's good in a quick diagnostic fix.