Do Something When is a system preference pane that allows the user to watch for drives mounting and un-mounting, allowing them to launch or quit applications, whenthese events happen.
DiskWarrior is the most highly decorated Mac disk repair utility ever. It repairs disks that no other program can repair. New hardware monitoring helps protect your data from drive malfunctions.
Disk Inventory X is a disk usage utility for Mac OS X 10.3 (and later). It shows the sizes of files and folders in a special graphical way called "treemaps".