I don't remember how I found out about Munseys. It's a website with links to thousands of out-of-print books, with over 1,500 pulp era novels. There's a lot of good stuff to be found here, as well as much that fits somewhere between excellent and awful. I downloaded and read a so-so novel called Alley Girl, by Jonathan Craig. There's no "alley girl" in it, which I didn't care about anyway. It's a about a hard-boiled sociopathic cop who tries to set up an innocent man for the electric chair so he can profit in more ways that one. It took me about an hour and a half to read and it made me forget about my 18-hour plane ride last week.
At the top of the chart, get Charles Willeford's Whip Hand (he ghost wrote it for Frank Sanders, or at least wrote most of it). It's about a kidnapping/murder seen through the eyes of different characters, and takes places in Texas. Willeford is one of the great hardboiled noir writers. I read everything of his I can get my hands on.