I was replying to a thread that was over 2 years old on 2 digit domain names. So I decided to post a new thread.
2 digit or two character domain names are allowed. But they have all been registered long ago. Some registrars seem to disallow them but that is for practical reasons. They are long gone.
A handful are available on domain resale sites. Only those with deep pockets have the money to buy them. This is the waterfront property on the Internet.
The best site to find those for sale is at http://sedo.com. They are dissapperaing fast. There are only 1296 2 character names. Owning one of these rare names gives a innovation cache and culture to the project.
A handful of the handful have a lease with option to buy. such as http:b3.com
These rare names are worth every penny.