While the number of cores in both embedded Multi-Processor Systems-on-Chip and general purpose processors keeps rising, on-chip communication becomes more and more important. In order to write efficient programs for these architectures, it is therefore necessary to have a good idea of the communication behavior of an application. We present a communication profiler that extracts this behavior from compiled, parallel or sequential C/C++ programs, and constructs a dynamic data-flow graph at the level of major functional blocks. In contrast to existing methods of measuring inter-program communication, our tool automatically generates the program's data-flow graph and is less demanding for the developer. It can also be used to view differences between program phases (such as different video frames), which allows both input- and phase-specific optimizations to be made. We will also describe briefly how this information can subsequently be used to guide the effort of parallelizing the application, to co-design the software, memory hierarchy and communication hardware, and to provide new sources of communication-related runtime optimizations.