Type-ins
Any Domain can become a type in.
Get visitors, offer great content and the word will spread. I found DNforum thanks to another site I had visited. Its a type in now for me, but who would have thought, no one. If it was a .whatever I still would have typed it in, why because the domain is descriptive and related to what I was looking for. Many people use search engines when searching for material, they dont just start typing in .coms or .nets into their browser, do they?
Any domain/extention can become a type in, its so simple to understand. Word of mouth, links and good search engine placement goes a long way.
If I find a site I like, it becomes a type in. Thus, any extension will do.
Mike