There are a lot of great tools in Jeanette Blomberg’s overview of Ethnographic Field Methods and Design [PDF 1.5MB] but one of my favorites is a low-tech industrial design technique for representing flows through an environment:
One such representation tool developed by the team was the Envisioner, which allowed a 3D scale model (1/4 scale and 1/2 scale to show different levels of detail) of the studied work settings to be constructed. The layout of particular offices and equipment and other artifacts used were depicted with foam core pieces which had magnetic bases that sat on a magnetic grid and could be easily moved and rearranged. A sheet of acetate sat on top of a Plexiglass roof so designers could make annotations, draw connections between objects, people, technologies and explore design ideas.
The Envisioner supported looking beyond the design of a particular technology by making the relationship between work, people and technology the focus of the representation.
That last bit about making relationships the focus should be a required attribute for any good service design tool.