GDB: The GNU Project Debugger
- Allows the user to view what is going on 'inside' another program while it executes -- or what another program was doing at the moment it crashed. Latest stable release is 7.0, 2009-10-06.
GNOME Bug Tracking System
- The place to submit bug reports for the GNOME desktop. The user can also search for reported bugs, browse the bug database, view the various reports relating to this site, and get help.
How to Report Bugs Effectively
- One of the best documents available on making bug reports. Read it, use it, and make developers happy campers! Available in many languages.
KGDB: Linux Kernel Source Level Debugger
- A source level debugger for the Linux kernel. It is used along with gdb to debug Linux kernel. KGDB is now merged into the Linux kernel mainline as of version 2.6.26.
Linux Kernel Tracker
- This is the Kernel Tracker system (based on Bugzilla) for posting bugs against the mainline Linux kernels (not distribution kernels). N.B.: This is for reporting kernel version 2.6 bugs only.
Mantis
- A PHP/MySQL web-based bug tracking system. Latest stable release is 1.1.8, 2009-06-08.
Nemiver
- A GNOME standalone graphical debugger for C/C++ programs.
Parasite
- A debugging and development tool that runs inside a GTK+ application's process, and provides detailed information on the UI, such as the hierarchy, widget properties, and X window IDs. It can also modify the application logic while the program is running.
The Cooperative Bug Isolation Project
- A distributed bug reporting system which uses remote reporting and statistical modeling to identify bugs in various open source applications (Evolution, Fedora, Pidgin, The GIMP, Gnumeric, Nautilus, and Rhythmbox), by watching the way the program behaves (anonymously) on users' machines and analyzing the results.
Valgrind
- A suite of code analysis and debugging tools for Linux.
Zzuf - Multi-Purpose Fuzzer
- A transparent application input fuzzer which finds bugs in applications by corrupting user-contributed data. Latest release is 0.12, 2008-06-13.