One reason I love the Coen Brothers films is because it opened the door for me to discover some of the things that influenced their films. Here's a few influences of note for some of their early films.
Blood Simple
Author - James M Cain
Novel - The Postman Always Rings Twice
Film - Detour
Raising Arizona
Animator - Chuck Jones
Film - Mad Max
Novella - Of Mice And Men
Miller's Crossing
Author - Dashiell Hammett
Film - The Glass Key
Barton Fink
William Faulkner
Biblical Parables
The Hudsucker Proxy
Directors - Frank Capra & Preston Sturges
Films - The Lady Eve & Executive Suite
Fargo
Film/Novel - In Cold Blood, Psycho & The Shining
The Big Lebowski
Author - Raymond Chandler
Novel/Film - The Big Sleep
Film - The Long Goodbye
Choreographer - Busby Berkeley
O Brother, Where Art Thou
Film - Sullivan's Travels
Musicians - Robert Johnson & Tommy Johnson
Politician - W. Lee (Pappy) O'Daniel
Film - The Wizard Of Oz