CiSE: Circular Spring Embedder
CiSE is an algorithm based on the traditional force-directed layout scheme with extensions to move and rotate nodes in the same cluster as a group. Further local improvements may be obtained by flipping clusters and by swapping neighboring node pairs in the same cluster, reducing the crossing number.
A web based demonstration of CiSE is here.
Integrated into Chisio
CiSE algorithm has been implemented in Chisio, a free editing and layout tool for compound or clustered graphs.
U. Dogrusoz, M.E. Belviranli, and A. Dilek, "CiSE: A Circular Spring Embedder Layout Algorithm", to appear in IEEE Transactions on Visualization and Computer Graphics.