I was thinking the other day that is would be great if there was a tool for Linux that you could use to build a series of common computer vision operations with a GUI and live preview for quick testing. What would be better is if the program could export these operations as OpenCV code and compile it in C/C++ so it can run in real-time. What would be even better than that is if someone else wrote the program so I didn't have to.
Today I found Harpia while testing Ubuntu 9.10 aka Karmic Koala. This is a great tool for developing ideas for computer vision tasks quickly and since it exports C code that links with OpenCV it is extremely fast.