quartz composer plug-in to write an image to disk. patch acts on the rising edge of the Write Signal input.
Download - GhostWriter-0.1.2.zip
to install from the binary download, move GhostWriter.plugin to ~/Library/Graphics/Quartz Composer Plug-Ins/, and to install from source, simply build the Build & Copy project target.
GhostWriter is not unlike ImageWriter, the developer example plug-in from apple, but offers further control of when to write the file to disk and the naming of the resulting file. build and runtime requires Mac OS X 10.6 or later.