... We have developed a user-friendly, highly interactive, ``Cluster Archive'' web site ( http://sca.ncsa.uiuc.edu/ ) that permits users to retrieve, analyze, and visualize archived data from extremely high-resolution numerical simulations of more than 100 X-ray clusters, spanning several orders of magnitude in luminosity and mass. ... To meet this need, we have developed a ``numerical observatory'' in a workbench style system that allows users to interact with archived simulation data over the Web. ...