I'll add to this, it's completely replaced my work search, and I haven't fallen back to a google search in months, even for very arcane Linux kernel internals.

I'll add to this, it's completely replaced my work search, and I haven't fallen back to a google search in months, even for very arcane Linux kernel internals. You can even manually prioritize certain sites, giving you a way to have a hand in building your own search experience.