On pages 15-62 of Sierpiński's Oeuvres Choisies, Tome I (large pdf), [1974, Hartman and Schinzel, eds.] there is a list of 720 mathematical publications that appeared 1906-1966, more than 100 other articles on history and mathematical vulgarization, 50 books and brochures and 12 polycopied course notes.
His most famous books probably are Hypothèse du Continu (1934, book [10]) and Elementary Theory of Numbers (1964, book [39]).
Addition: The list in the Oeuvres Choisies is intended to be complete: quoting the avant-propos on page 7.
La liste complète des travaux scientifiques de Sierpiński en comporte 720. Les travaux choisis pour être publiés se distinguent soit par leur actualité, soit par leur importance pour le développement des mathématiques, soit encore par la beauté intrinsèque des résultats obtenus et des méthodes employées.
Wikipedia claims without source that there are 724 mathematical publications by Sierpiński.
In general, reasonably complete lists of publications and biographical information can often be found in collected works, e.g. Serre. This only works for the more famous mathematicians. Sometimes obituaries contain a short commentary on selected works and lists of publication.
For more modern authors (who only published after 1940) you can get a first overview by searching MathSciNet or the Zentralblatt, provided that you have access. Most scientific libraries have a subscription to these services. Searching for the Author's name with Author/Related in MathSciNet also gives results on articles about the author.