that's some good sh*t

Solution 1:

Cheech and Chong used the term "Good Shit" in their drug move "Up in Smoke" (1978). The usage in drug subculture predates that. Good shit goes back to the early 1950's w respect to heroin quality: new Partridge dictionary of slang and unconventional English

Solution 2:

While the info about solidarity markers and bollocks is true and relevant to the long-since-completed meaning acquisition, I think in the case of "shit for making websites," it's simply a matter of the shit being used to mean stuff. At the risk of wielding too sharp a razor, don't think it's any more complicated than that.

For the "nigga" question, consider John Lawler's solidarity comment and the discussion at Brian Hooper's link.