Ron Eglash's Erdös number 3:

Erdös–Goldberg: "Cutting a Graph into Two Dissimilar Halves" (1988)
Goldberg–Krishnamoorthy: "Finding Communities by Clustering a Graph into Overlapping Subgraphs" (2005)
Krishnamoorthy–Eglash: "Audience as Co-Designer: Participatory Design of HIV/AIDS Awareness and Prevention Posters in Kenya" (2006)