Hopefully I put this in the right spot, but if not, please feel free to move this. 
If you read, or write, the classic hard-boiled (or noir, or more generally detective fiction) genres, I simply came across a website I'd like to recommend as reference: Thrilling Detective.
It's crammed full of useful information about your favourite authors and their books, biographies, adaptations of their work -- what you'd generally expect to find -- as well as unexpected treasures, like Essays and Articles, Authors' Wit and Wisdom (e.g. Frank Ryan's Golden Rules about how to write an Armed Robbery, or Robert B. Parker about how to write).
My favourite? Christa Faust's Ten Rules to Writing Noir. She distils it down to ten rules that apply not only to noir, not only to detective fiction, but to almost any genre. Recommended!

If you read, or write, the classic hard-boiled (or noir, or more generally detective fiction) genres, I simply came across a website I'd like to recommend as reference: Thrilling Detective.
It's crammed full of useful information about your favourite authors and their books, biographies, adaptations of their work -- what you'd generally expect to find -- as well as unexpected treasures, like Essays and Articles, Authors' Wit and Wisdom (e.g. Frank Ryan's Golden Rules about how to write an Armed Robbery, or Robert B. Parker about how to write).
My favourite? Christa Faust's Ten Rules to Writing Noir. She distils it down to ten rules that apply not only to noir, not only to detective fiction, but to almost any genre. Recommended!