For Experimental Economics you should check out the Interdisciplinary Center for Economic Science and the International Foundation for Research in Experimental Economics. Also look at Charles Holt's web page, and Al Roth's page and the Economic Science Association web site. Check out Holt's Y2K bibliography of experimental economics publications up to 12/29/1999. Another good site for NeuroEconomics is the one maintained by Richard Peterson.
For NeuroImaging a very good resource site is the Cognition and Neuroimaging Laboratories at the University of Arizona. Check out their glossary and links pages. A really nice education site is maintained by Eric Chundler, he has a great neuroscience for kids page. The Wellcome Department supports the SPM software package for the analysis of brain imaging data sequences.