Okay, so not quite untold, but that sounds more enticing than "once-told."
Much as I'd like to, I can't expedite the 2012 publication of my book on Bill Finger (say it with me: uncredited co-creator and original writer and primary visual architect of Batman). To get your Finger fix in the meantime, I'll be sharing tidbits about Bill that didn't make it into the manuscript.
First is one of my favorites.
Jack Liebowitz, onetime and longtime head of DC Comics, promised to buy Bill a car if he would submit his scripts on time. Bill continued to be late—and apparently never got his license anyway. He didn’t seem to need one. For most of his life, he stayed in or near New York. When he went to Texas for a seder, it was most likely by train. (He also didn’t fly.) When he and his wife Portia vacationed in Provincetown, Massachusetts, she probably drove.
Writer Will Murray turned me on to this anecdote in 2006, though he couldn't recall where he'd seen it. Thanks to Will and to the unstumpable John Wells for locating the source (Gil Kane quoted in The Comics Journal #186, April, 1996).