This is by no means news, but I'm fascinated to learn of a website for books about or set in alternative histories. I've enjoyed some books in this genre in the distant past, for example SS-GB by Len Deighton and, some years later, the eerily similar Fatherland by Robert Harris. Maybe the rest of the world knows about this site and I'm the last to know, but in case there are a few others like me, here it is: Ucronia, the alternate (sic) history list. In short, the site is "a bibliography of over 2900 novels, stories, essays and other printed material involving the "what ifs" of history......one or more past events are changed and the subsequent effects on history somehow described. This description may comprise the entire plotline of a novel, or it may just provide a brief background to a short story. Perhaps the most common themes in alternate history are "What if the Nazis won World War II?" and "What if the Confederacy won the American Civil War?" For more about alternate history and this bibliography, please read the extended introduction."
One listing is an anthology of alternative history crime stories by Lou Anders (see here). Looking round the site, I can't always quite see where science fiction ends and alternative history begins, but there are plenty of gems to be found. Here is one title by an excellent author that sounds intriguing: Robert Barnard: Mozart Mysteries. "What if during a visit to England to show off his prodigy son to the English court, Leopold Mozart decided to remain in England as a result of being accidentally overpaid by a royal courtier?" I've never come across these titles, possibly because they were written under a pseudonym, but I shall have to look out for them now.