I like the idea of a hacker centric browser that peels away the cruft that typical end users like to see and makes Inspecting HTML/CSS, Debugging JS, and Performance Diagnostics a first class citizen in a better way than Web Inspector or Firebug do.

Being able to have an easy way to switch rendering engines on the fly but retain the same tooling would also be pretty damn awesome.

While a community based effort for this would be cool, I would totally pay money for something like this.