St. Clair Software has released Jettison 1.4 (http://tinyurl.com/kvonedl), an update to their Mac OS X application that automatically ejects external drives before your Mac goes to sleep. It eliminates the hassle of manually ejecting Time Machine backup drives, network server volumes and flash drives.
Just close the lid of your MacBook and Jettison does it for you. Version 1.4 adds hot keys to eject and remount disks, remounting of flash drives, and more robust operation.
Jettison 1.4 requires Mac OS X 10.6 or higher. It’s a free update for registered users. For new users the cost is US$4.95.