All I see there is a "domain for sale" page...
A lot of the early domains are still active. But most of them eventually changed hands, so they don't still have the same contents that they originally had.
If you got into your time machine and went back to 1992 or 93, you could register a single letter domain (assuming you had an Internet connection, which wasn't easy to get at the time, and assuming you could figure out how to register a domain, which also wasn't easy). There are only six single letter .com, .net or .org domains still registered, one of them is x.com, which used to be online banking, and eventually turned into PayPal.
If you owned a single letter domain today, you could sell it for enough money to buy an island somewhere and build a private resort and discotheque. You know, so you and your friends could boogie with your toes in the sand and swim around naked in the Caribbean sea.
I know this is boring shit to just about everyone in the world, but I find it very interesting. Oddly enough, it isn't really written about very much. We're losing a lot of early Internet history.
This guy does a podcast that covers a lot of it, but he only goes back to the first web browsers, and a lot of things happened before that...