Here are some of the most notable:
* Sleeping Murder (1976): This was the final Poirot novel, completed in 1975 but published after Christie's death.
* Postern of Fate (1973): Originally intended for a collection of short stories, this was released as a novel after Christie's death.
* The Big Four (1927): This novel was originally published in 1927 but was reissued in 1977, adding a previously unpublished chapter written by Agatha Christie in 1956.
* The Hound of Death (1933): Originally a short story, this was expanded into a full-length novel by a team of writers after Christie's death.
There are also several other posthumous publications of short story collections and non-fiction works.
So, while there wasn't one specific book published *after* her death, there were several books published posthumously, including the final Poirot novel.