Related to both Talmudic commentaries and Responsa literature, Novellae (or hidushim) were generally intensive discussions on various passages in the Rabbinic literature (including Talmud, Mishnah etc.) In contrast, commentaries usually contained smaller comments which ran from page to page to help clarify passages in the Rabbinic literature.
The novellae of the Aharonim differ from those of the Rishonim in that they include discussions of how to apply the laws in the Talmud to new ideas, issues, or circumstances.
Some early authors of novellae included Joseph Ibn Migash, Abraham b. David of Posquieres (RaBaD), and Meir b. Todros Abulafia, Solomon b. Abraham Adret, Yom Tov b. Abraham Ishbili, Nissim b. Reuben Gerondi, Nahmanides, and Joseph ibn Habiba.
Look in BM 504.2
Includes the Hebrew texts of the Tanakh, Talmuds, early commentaries, codes, and many responsa. Searching is allowed from anywhere, more features are available (saving, printing, etc.) from the HUC campus or through the Jewish Studies Portal.
Many older rabbinic works are available in PDF form on this site.