Diskus is a high-level hard drive diagnostic and limited repair tool. It checks the disk geometry by writing numbered IDs into the sectors of the hard drive. Later one can verify that these sector-IDs on the disk are still correct, thereby detecting data which was not correctly written. There is an option to "freshen" the data on your harddrive, which will read and rewrite the sectors. With modern drives this will re-map defective sectors.
YASIS is a very detailed sysinfo script that displays individual stats or grouped info. It only requires lspci and common tools found in any distribution. Check the page for example outputs. It displays distribution/kernel, CPU count/cache/load, disk/swap/RAM used/free, network info/speed, CPU temp/fan speeds, X environment info (wm/de and display info), bandwidth speeds, and more.
psinfo shows process information and statistics using the kernel /proc interface. This information includes: process state, environment, arguments and flags; CPU usage; scheduling; I/O usage; virtual memory status; pagefaults; capabilities; and signals. psinfo is useful for providing a detailed view of the current state of an application when diagnosing issues or performance problems.
Nagstamon is a Nagios status monitor with a UI that resides in the systray or as a floating statusbar on your desktop. It informs you in realtime about the status of your Nagios, Icinga, Opsview, Ninja, Check_MK/Multisite, Centreon, or Thruk-monitored network. It alerts you with sound and visual notification. Failed hosts and services are easy to connect with by SSH, RDP, and VNC. Custom actions can be run on certain events. It works best with GNOME, but also with KDE, Mac OS X, and Windows.
Zoom is a low-overhead graphical and command line profiler for Linux. Profiles are system-wide, precise down to the instruction level, and capture complete backtraces of C/C++/ObjC/Fortran/Assembly code. This lets you see exactly where time was spent, what code was running (user or kernel), and how that code was called. Drill down into a specific symbol, and Zoom shows source and assembly annotated with general and processor-specific tuning advice. It saves profiles as a single, self-contained session file that can be emailed or attached to bug reports. This lets you share what you find with colleagues or archive it for later review. Zoom also supports remote network profiling and scripting, making it ideal for embedded or server systems and automated workflows.
UnusedPkg is a diagnostic tool to search the oldest unused packages in your Linux system. UnusedPkg prints a sorted list with the size and number of days that a package has been idle. This helps you determine what packages can be manually removed to clean the system. It supports any apt-based distribution (tested on Debian and Ubuntu) and Slackware.