AspectMaps is an interactive software visualization tool built to aid the understanding of aspect-oriented software systems. AspectMaps visualizes selected join point shadows (a.k.a. shadow points): locations in the source code that at run-time produce a join point. AspectMaps visualizes the shadow points where an aspect will execute, and if multiple aspects will execute, the order in which they are specified to run.
It is developed by Johan Fabry.
More information about it can be found on the official page.
The code is available on SqueakSource: http://www.squeaksource.com/AspectMaps.html