Modeling and analogy are commonly used to identify the part that a metal may play in the structure or function of a new protein which has been recognized by structural genomics. Mespeus ( http://mespeus.bch.ed.ac.uk/MESPEUS_10/) lists metal protein interactions whose geometry has been experimentally determined and allows them to be visualized. This can contribute to the modeling process. The use of Mespeus is described with a series of examples.