Parallel Fractal GPL is a numerically-intensive parallel graphics application that uses the MacMPI_XUB.c library for communications. The same source code compiles both in CodeWarrior, for creating Carbon CFM apps for OS 9 and X, and in Xcode, for creating a universal application on both Intel and PowerPC.
Blinged JSON Validator is a free app to validate JSON files with syntax highlighting, whitespace indentation, error messaging, and hotkeys.
