This site from Ole Miss contains Williams's biography plus links to analyses of his work. It is a great introduction to the playwright's life. And it has pictures!
The New York Times archive of all things Williams-related is fascinating. There are personal essays penned by Williams himself, original reviews of the first runs of his plays, and commentary on the playwright and the books about him. This is a very entertaining place to poke around.
Tennessee Williams's entry in the PBS American Masters series has the playwright's biography and links to other sites about him. It also has a video clip from Baby Doll, a film Williams wrote that critics lambasted as filthy.
This is the official site of an annual gathering for people who really, really, really love Tennessee Williams. Williams lived in New Orleans for several years and enjoyed a close and special bond with the city. The festival is a five-day celebration of literature, theater, and the arts, and includes a one-act play contest.
If the paper that you're writing for your class turns out to be utterly amazing, submit it here—the official site of hardcore Williams scholars. You can also search the journal's online archives for back copies of critical articles on the playwright.
If the timeline we've put together for you here at Shmoop isn't quite good enough for you (gasp!) then check out this one compiled at the Theater Database. It's got a detailed chronology of Williams's life and times.