The libexplain project provides a library that may be used to explain Unix and Linux system call errors. This will make your application's error messages much more informative to your users. The library is not quite a drop-in replacement for strerror, but it comes close: each system call has a dedicated libexplain function.
RFDUMP is a GUI to edit the "User Data Fields" on RFID tags and to test if a tag is protected against reading or writing. It implements a real life cookie on RFID tags. The tags that are supported for reading, writing, and editing are ISO 15693, ISO 14443 A, ISO 14443 B, SR176(1,2), Tag-it®, and I-Code®.
Torta shows you where your disk space is going. It uses the graphical format used by filelight to represent disk usage. Unlike filelight, it can be run on a computer with no graphical environment: it generates a Flash file that can be consulted, locally or remotely, using any browser that has the Flash plugin installed.
i.Task is a small and fast process viewer and terminator for Linux. It lists all running processes and associated information, allowing the user to sort by any column. The information displayed includes, process name, PID, CPU usage/time, owner, priority, threads, memory usage and process arguments. The context menu allows you to send TERM or KILL signals to a process. The main benifit of i.Task, apart from the easy-to-use interface, is that it has far fewer dependencies that other available process viewers.