Basic Library List in Number Theory Compiled by the Mathematical Association of America (MAA). This site sub-divides Number Theory into Introductory Texts, Expositions, Elementary Monographs, Primes and Factors, Algebraic Number Theory, Analytic Number Theory, Modular Forms, P-adic Fields, Special Topics, Cryptography, History and Biography and Classic Works.
Number Theory Books from 1996 A comprehensive, well-linked and well-maintained list of Number Theory books. The Number Theory Web, which houses this web page, contains links to pre-1996 books.