Nitro Technologies Memory Checker makes tracking down memory leaks in C programs simple. It wraps strdup / strndup / calloc / malloc / free and tracks memory usage, allowing a report containing information on all allocated memory (and what function allocated it, which line, which file, etc.) at any time during the running of your program.
Sedsed is a Python script that masters sed scripts. It generates sed debug files in sed, which lets you debug scripts with your own version of sed (Linux, DOS, etc.). It's also a script beautifier, doing indentation and spaces/comments formatting. It can also convert sed scripts to colorful HTML files.
jGRASP integrates the Control Structure Diagram (CSD) seamlessly and unobtrusively into source-code editing for Java, C, C++, Objective-C, Ada, and VHDL. The CSD is a control flow and data structure diagram that fits into the space normally taken by indentation in source code. Its intention is to improve the readability of source code. The CSD also enables source code folding in a meaningful way, based on code structures. jGRASP provides lots of editing features, an integrated Java debugger, UML dependency diagrams for Java, configurable colors and font size, and click-to-error for compile and runtime (Java stack dumps) errors.