Alexandre Stefanov has long maintained a list of online math texts and other materials at Geocities; this material has now been moved to 110MB Hosting. Because these resources may be of interest to our readers, we present here a modified version of Stefanov's list as of November 18, 2009.

Introductory Number Theory

• An Introduction to the Theory of Numbers, by Leo Moser
• Number Theory Notes for students at IMO level, by Naoiki Sato
• Elementary Number Theory, by William Edwin Clark
• Lecture notes on elementary number theory, by Bruce Ikenaga
• Exercises with solutions on elementary number theory, by Nigel Byott
• Elementary Number Theory, notes by Michael Filaseta

p-adic numbers

• Lecture notes on p-adic numbers, by Andrew Baker

Arithmetic Geometry

• Open Questions in Arithmetic Algebraic Geometry, by Alice Silverberg

Fermat's Last Theorem

• William Hammond's Fermat Archive
• Review of Alf van der Poorten's Notes on Fermat's Last Theorem, by Andrew Granville

Algebraic Number Theory

• Survey of Euclidean Number Fields, by Franz Lemmermeyer
• A Computational Introduction to Number Theory and Algebra, by Victor Shoup
• A Course In Algebraic Number Theory, by Robert B. Ash
• Elementary and Algebraic Number Theory, by Ivan Fesenko
• Algebraic Number Theory, by Jim Milne
• Algebraic Number Theory, by Robin Chapman
• Invitation to higher local fields, by Ivan Fesenko and Masato Kurihara (editors)
• Algebra and Number Theory, by Andrew Baker
• Elementary Number Theory, by William A. Stein
• Notes for Dick Gross' Algebraic Number Theory Course, by S. Sather-Wagstaff
• Algebraic Number Theory & Introduction to Automorphic L-functions, by Ching-Li Chai
• Lecture notes on Algebraic Number Theory, by Jerome William Hoffmann
• Introduction to Number Theory, by Franz Lemmermeyer

Analytic Number Theory

• Course notes for analytic number theory, by Graham Everest
• Distribution of Prime Numbers, lecture notes by William Chen
• Introduction to Analytic Number Theory, by Noam Elkies