Java Debugging with Statement Aspects provides the possibility to skip certain statements from being executed during debugging. It lets you add your custom logic before and after execution of certain statements. It provides the possibility of tracing at the granularity of line numbers without touching the source code.
KEDR is a framework to facilitate dynamic analysis of kernel modules in Linux ("KEDR" is an acronym for "KErnel-mode Drivers in Runtime"). KEDR allows you to intercept the calls that a kernel module makes to the functions exported by other modules and by the kernel proper. The tools provided by the framework can record the arguments and return values of these functions to a trace, perform fault simulation according to user-defined scenarios, and check the kernel modules for memory leaks and some other kinds of problems. Custom data collection and analysis tools for the Linux kernel can also be built on top of KEDR framework.
python-tracing provides the Python library "tracing" to help with logging debug messages. This module provides a couple of functions for logging debug messages. It is sometimes practical to add a lot of debugging log messages to a program, but having them enabled all the time results in very large log files. Also, logging that much takes quite a bit of time. This module provides a way to turn such debugging or tracing messages on and off, based on the filename in which they occur.
PHP Error aims to make understanding initial error reporting as fast as possible. When an error strikes, you get a full syntax-highlighted stack trace, with code snippets from the relevant files and improved error messages, displayed with CSS3. It works for AJAX requests, too, with no JS changes or plugins required.
pymiproxy is a small, lightweight, man-in-the-middle embeddable proxy capable of performing HTTP and HTTPS (or SSL) inspection. The proxy provides a built-in certificate authority that is capable of generating certificates for SSL-based destinations. Pymiproxy is also extensible, and provides two methods for extending the proxy: method overloading and a pluggable interface. It is ideal for situations where you're in dire need of a proxy to tamper with out- and/or in-bound HTTP data.