My colleagues with ACCIS (Association of College Counselors at Independent Schools) have been compiling a list of colleges and universities that superscore the ACT.
The list continues to grow.
Here is the most updated list as of March 2012:
Beloit College
Boston College
Brandeis
Clemson University
Drexel University
Dickinson College
Emory University
Florida State University
Georgia Institute of Technology
Gettysburg College
Hamilton College
Haverford College
Lehigh University
UMass-Amherst
McGill University
Middlebury College
Northwestern University
RPI
University of San Diego
Santa Clara University
Sewanee: University of the South
Swarthmore College
Trinity College (CT)
Trinity University (TX)
Union College
Vassar College
Williams College
University of Vermont
Pepperdine Univ.
Cal Tech
Connecticut College
Soka University
Tufts Univ.
Westmont College
UNC Chapel Hill
Amherst College
Babson College
University of Colorado
Eckerd College
Elon University
George Washington University
University of Illinois
University of Indiana
Lawrence University
Loyola Marymount University
University of Miami
Northeastern University
University of Puget Sound
Stanford University
Washington & Lee University
Washington University in St. Louis
Wesleyan University
Colorado College
DePauw University