http://www.romhacking.net/docs/343/
This was a recent submission we got. I found this document so interesting, I thought I'd make a topic just to get people aware of it's existence.
This is a full explanation for why the 'minus world' exists, how it is triggered, and why it does what it does. It also includes code explanation.
If you've ever wondered about this glitch, this document explains everything in detail not to mention as a side effect gives you a good understanding of how SMB works.