Three universities with BPM programs — Humboldt University, Eindhoven University of Technology and the Queensland University of Technology — are running a survey on how business process models can be improved in terms of understandability. You can take the survey here, although it’s specifically for those who model using event-driven process chains (EPC). As a participant, you’ll have access to the results of the survey, plus the chance to win a recently-released book, Metrics for Process Models.
I gotta warn you this survey will take a little time.