Websites
L'Engle's Official Website

This website, maintained by L'Engle's family, includes news, links, media, and a bibliography.
Movie or TV Productions
Walt Disney's Made-for-TV A Wrinkle in Time

When asked in a Newsweek interview whether this movie adaptation met her expectations, Madeleine L'Engle replied, "Yes, I expected it to be bad, and it is."
Documents
L'Engle's Newberry Award Acceptance Speech

Discussing A Wrinkle in Time, writing, and fantasy.
L'Engle's Margaret Edwards Award Acceptance Speech

In which she discusses several of her books, including Wrinkle, and also aliens.
Video
A Physicist Explains the Tesseract

And also draws lots of cubes really fast.
Audio
How to Pronounce the Author's Name

Just in case you were wondering.
NPR Interview with Madeleine L'Engle

Talking about the movie adaptation.
Another NPR Interview

On the links between creativity and religion.
Obituary, Also from NPR

With extensive audio clips from interviews with the author when she was still alive.
A Wrinkle in Time Audiobook
SPONSORED

Purchase and download the Audiobook from Random House Audio
Images
Animated .gif of the Tesseract

In case Mrs. Whatsit's skirt demo wasn't enough.