DiskScan scans the entire surface of a disk, alerts when a sector is unreadable, and uses the read timing to warn when a sector is having problems. It will tell when a disk has failed and already has bad sectors and also when the disk is near failure and takes too long to read the data.
Gpart is a small tool which tries to guess which partitions are on a PC harddisk in case the primary partition table was damaged. It works by scanning through the device (or file) given on the commandline on a sector basis. Each guessing module is asked if it thinks a filesystem it knows about could start at a given sector. Several filesystem guessing modules are built in, and others can be added dynamically.
Web Secretary is Webpage change notification (monitoring) software. It goes beyond the normal functions offered by such software by detecting changes based on content analysis, making sure that it's not just HTML that changed, but actual content. You can tell it what to ignore in the page (hit counters and such), and it can mail you the document with the changes highlighted or load the highlighted page in a browser.