I thought the same thing before I opened the article; however, I had heard of two of them.
But this forum is full of hackers who create web apps and even though the browsers may be fun for testing, I am doubtful any of those are great tools for dev work seeing as they aren't anything close to even a trivial piece of the browser market share.
Either way, I was appreciative of learning about new browsers. A couple of them look like the could be worth candidates to try firebug on =]
Wow, I'm genuinely irritated at myself for now having heard about Lunascape. Trying it out now, and am impressed so far, recommended for web devs/designers out there: