The Midrash Project at the Schechter Institute of Jewish Studies is publishing a series of books on Midrash, including critical editions of at least eight midrashim. Each critical edition will present the midrash based on the best manuscript and will include selected variant readings, reference to parallel sources in Rabbinic literature and a critical commentary. The series is being edited by Profs. David Golinkin and Shamma Friedman.
Two books from the series have been published thus far and can be purchased from the Schechter Institute Bookstore: a second hebrew edition of Prof. Levi Ginzberg's Legends of the Jews (three volumes and an index volume) edited by Prof. Golinkin and Midrash Shmuel, the first critical edition in the series, edited by Prof. Berachyahu Lifshitz. Synoptic editions of Midrash Shmuel , Esther Rabbah, and Kohelet Rabbah are available online at this site (see below). Critical editions of A New Midrash on the Torah and Esther Rabbah will be published in 2013.
Legends of the Jews, Prof. Levi Ginzberg, second Hebrew edition; Prof. David Golinkin,ed.
Midrash Shmuel, Prof. Berachyahu Lifshitz, ed.
A New Midrash on the Torah, Dr. Gila Wachman, ed.
Midrash Esther Rabbah, Prof. Yosef Tabori and Dr. Arnon Atzmon, eds.
Kohelet Rabbah, Prof. Marc Hirshman and Dr. Reuven Kiperwasser, eds.
Ruth Rabbah, Prof. Meron Bialik Lerner, ed.
Eicha Rabbah, Dr. Paul Mandel, ed.
Shir HaShirim Rabbah, Dr. Tamar Kadari, ed.
Midrash on the Repentance of the Prophet Jonah, Dr. Tamar Kadari, ed.