The GeoDa Center for Geospatial Analysis has relocated to the University of Chicago. You may find the site, as well as associated software downloads and documentation, at spatial.uchicago.edu.
Arizona State University's home for Geographic Information Science research is now named the Spatial Analysis Research Center (SPARC). Learn about many of its initiatives and researchers here.
GWR4 downloads area available here. (This is a geographically weighted regression tool developed by Professor Stewart Fotheringham.)