Swim Lanes - Process map diagrams
A swim lane (or swimlane) is a type of process flow diagram that depicts what or who is working on a particular subset of a process.
The swim lane flowchart differs from other flowcharts in that processes and decisions are grouped visually by placing them in lanes. Parallel lines divide the chart into lanes, with one lane for each person, group or subprocess. Lanes are arranged either horizontally or vertically, and labeled to show how the chart is organized.
The longitudinal direction represents the sequence of events in the overall process, while the lateral divisions depict what subprocess is performing that step. Arrows between the lanes represent how information or material is passed between the subprocesses.
When used to diagram a business process that involves more than one department, it can clarify not only the steps and who is responsible for each one, but how delays, mistakes or cheating are most likely to occur.
Source: http://en.wikipedia.org/wiki/Swim_lane
Tutorial: http://www.infomanagementcenter.com/enewsletter/200603/fourth.html