Good interview giving the inside story of one guy who made the dead frontier mmo. Gives alot of hints and tips for anyone else trying. I think the really interesting part is that he'd made several single player versions of dead frontier (being paid for some, which is significant to development), which helped him nail down the game he wanted to make before he made it massive.
I think that's the key. Make a game that you would enjoy in a single player format and it WILL make a great mmo game!
And apparently the interview was held by the maker of Golemizer, which is also a one man MMO!
It's a really good feeling that individuals can decide their own fate on these things!