I wonder how they managed to get such a short domain name, I thought 3 characters was the minimum. And it must cost quite a lot.
I own http://0k.nu and I just regularly registered it.
I also own http://π.pw and http://ಠ.com .
Single-letter domains for .org, .net, and .com are/were reserved, although there are exceptions such as http://www.x.org. Other TLDs may vary.
.monash used to also have the same property (if I am not mistaken), until they realized this fact, I imagine.
The trailing . makes it fully-qualified.