Wbumount lists the processes which are using a certain mount point, thus preventing it from being removed. This is meant to assist the user who receives a "umount: device is busy" message when trying to remove a disk. The list is updated once every second. When all processes are gone, the "umount" and "eject" buttons are activated. This teaches a desktop user how to peform the right actions to free a mount point in an interactive way.
dstat is a versatile replacement for vmstat, iostat, netstat, nfsstat, and ifstat. It includes various counters (in separate plugins) and allows you to select and view all of your system resources instantly; you can, for example, compare disk usage in combination with interrupts from your IDE controller, or compare the network bandwidth numbers directly with the disk throughput (in the same interval).
Spike Asset Manager (SAM) is a cross-platform framework for probing a system for components and reporting them. It includes a driver file that probes for components commonly found in a LAMPJ stack (Apache, MySQL, PHP, Tomcat, etc). It can find multiple versions that are installed, query the RPM database, and indicate whether components are running.
CaiCai is a network and services monitoring system. It performs tests for ping, DHCP, POP3, SMTP, FTP, etc. It does not require additional software installed on the remote side. It is fully configurable. It provides instant reports (via an HTML page), logs, statistics, and sound alarms.
Rugg is a hard drive and filesystem harness tool that allows you to test and benchmark drives and filesystems by writing simple to complex scenarios that can mimic the behaviour of real-world applications. Test scenarios can be implemented using Rugg's compact and versatile domain specific language.
apache-top provides real-time display of the active processes from a remote apache server. It shows: the active apache processes with the associated PID, the status, the active seconds, the CPU usage, the associated VirtualHost, the accessing IP and the request (POST or GET, the file being accessed, and the used protocol); the server uptime and the time it was last restarted; CPU usage; requests per second, Kb per second, and the average Kb per request; the number of active and inactive processes; and a graph with the inactive and active processes and their status.
net-status-monitor is a simple console script to test whether Internet connectivity is working. If it is, the script tells you the external IP address (in case your dynamic DNS provider is down). If not, it tries to find the point where the connectivity fails. The output is quite simple, so you can put it on your grandmother's PC. "Just tell me what the read line says" should give you enough information.