  Digital libraries must reach out to users from all walks of life, serving
information needs at all levels. To do this, they must attain high standards of
usability over an extremely broad audience. This paper details the evolution of
one important digital library component as it has grown in functionality and
usefulness over several years of use by a live, unrestricted community. Central
to its evolution have been user studies, analysis of use patterns, and
formative usability evaluation. We extrapolate that all three components are
necessary in the production of successful digital library systems.
