Below are links to online whole text or nearly whole text of some rabbinic literature. I list only webpages or Google Books which number the sections and thus are easy to use. This collection of links is updated from time to time.
Such primary sources are useful when one reads articles about the Bible which quotes rabbinic materials to prove a point about social customs or Jewish methods of interpretation etc. Sometimes we wish to look up the context of the quoted rabbinic passage to ascertain what was really said.