Aspect colouring is an idea I had in 2005, when apparently I did not yet care about the difference between aspects and concerns. It would have been better to call it concern colouring, but I'm not going to change the name after four years.
I wrote a motivation and explained a trivial implementation in a text entitled "from syntax colouring to aspect colouring".
The aspect colouring tools (to be used with the editor vim) can be downloaded here: