"Midrash" in general refers to commentary on the Bible. Often though, it is used to describe particular collections of midrash written from the 2nd to the 10th century, with a few later works as well. The midrash include commentaries, interpretations, stories that illustrate biblical passages and sermons.
Below is a list of most of the Aggadic Midrash by period. You'll notice that "Midrash Rabbah" is not listed. In the 1500's, collections of midrash on the Torah and then later including midrash on other parts of the Tanakh were published together as "Midrash Rabbah" (i.e. Genesis Rabbah, Exodus Rabbah, Leviticus Rabbah, etc.)
Eichah (Lamentations) Rabbah
Pesikta de-Rav Kahana
Midrash Iyyov (Job)
Pirkei de-Rabbi Eliezer
Kohelet (Ecclesiastes) Rabbah
Canticles (Songs) Rabbah
Baraita of Samuel
Targum sheni (on Esther)
Most individual works of midrash are shelved in BM 517.
Collections of aggada (from the midrash and/or Talmud) are in BM 516 (including Sefer ha-Agadah and Ein Yaakov)
Other translated collections are in BM 512
Books about Midrash are in BM 514
Halakhah in the Midrash are in BM 515
Remember that your local librarian is there to help!
Bar Ilan Responsa Project
Includes the Hebrew texts of the Tanakh, Talmuds, early commentaries, and many responsa http://www.responsa.co.il/
More options are available to HUC students and faculty by accessing the Responsa Project through the Jewish Studies Portal
The Legends of the Jews / by Louis Ginzberg
Many older rabbinic works are available in PDF form on this site.
PIRQE RABBI ELIEZER electronic text editing project / Lewis M. Barth, editor
While the Library thinks that these sites are useful, their content is not under our control and may express views that are not shared by the Hebrew Union College-Jewish Institute of Religion.
If you have any further questions about finding information on this, or any other topic, ask your local HUC-JIR librarian or email us using the form on the campus library homepage.