A massive collection of SNES technical documents. This is an old collection, though, and there are errors, but still definitely worth a look.
The documents in this collection were made by various authors, and compiled together by Qwertie. This very zip file was hosted on Qwertie's own Geocities page, until Yahoo took down Geocities last month. I am posting it here for 2 reasons: I don't believe this wealth of information should die, and because I do believe this information will benefit ROM Hackers here on SMW Central.