I want to give particular thanks to my early mentors, namely Skip Scriven, whom I worked with as an undergraduate at the University of Minnesota, and Dale Rudd, who was my Ph.D. advisor at the University of Wisconsin. Thanks also to all my graduate students, and others who have worked in my group. I think it is well known that it is these students who do most of the work I also want to thank the various funding agencies and others who have supported this work, both in terms of dollars and computing time. These include the National Science Foundation, the ACS Petroleum Research Fund, the Environmental Protection Agency, the Department of Energy, the Army Research Office, the Dreyfus Foundation, Sun Microsystems, Cray Research, IBM, Dow Chemical, Du Pont, Shell Oil, the University of Illinois at Urbana-Champaign, and the University of Notre Dame.