A Mechanical Proof of Quadratic Reciprocity
   A paper by David M. Russinoff describing the use of the Boyer-Moore theorem prover in mechanically generating a proof of the Law of Quadratic Reciprocity. PS/PDF.
   http://www.russinoff.com/papers/gauss.html

Active Elementary Number Theory
   Interactive (Javascript) expression of a number as a sum of two squares.
   http://www.faust.fr.bw.schule.de/mhb/taupaeng.htm

Covers, Sumsets and Zero-sums
   A unified approach to covering systems, restricted sumsets and zero-sum problems by Zhi-Wei Sun.
   http://math.nju.edu.cn/~zwsun/csz.htm

Fermat's Little Theorem
   With notes on Carmichael numbers and the life of R.D. Carmichael.
   http://www.pballew.net/FermLit.html

Frequently Asked Questions
   Number Theory section of the sci.math FAQ list.
   http://db.uwaterloo.ca/~alopez-o/math-faq/node21.html

Hakmem Continued Fractions
   Some notes from the MIT collection. Includes Gosper's algorithms for CF arithmetic.
   http://www.inwap.com/pdp10/hbaker/hakmem/cf.html

Infinite Series Theorem
   Addresses the question whether a series of rational functions converges to a rational number.
   http://www.infiniteseriestheorem.org/

Integer Relations
   To determine linear integer dependence among numerical constants and to determine the minimal polynomial of an approximate algebraic number. Interactive or via email.
   http://oldweb.cecm.sfu.ca/~aszanto/IntegerRelations/

Klein Polyhedra
   Examples and algorithms for computing Klein polyhedra, also known as Arnold sails or veils (voiles), by Keith Briggs.
   http://keithbriggs.info/klein-polyhedra.html

L-Functions
   Classified by degree, then by level, then by eigenvalue, then by root number.
   http://www.math.okstate.edu/~loriw/start/start.html

Lehmer's Conjecture
   That the Mahler measure of an algebraic number is bounded away from 1. Pages by Michael Mossinghoff, UCLA.
   http://www.cecm.sfu.ca/~mjm/Lehmer/lc.html

Linear Independence Measures for Logarithms of Algebraic Numbers
   Michel Waldschmidt. Cetraro summer school lectures, July 2000.
   http://www.mathp6.jussieu.fr/~miw/articles/cetraro.html

MathPages: Number Theory
   Kevin Brown's collection of sci.math postings related to number theory topics.
   http://www.mathpages.com/home/inumber.htm

MathWorld Number Theory
   Index to articles in Eric Weisstein's MathWorld in the area of number theory.
   http://mathworld.wolfram.com/topics/NumberTheory.html

Noncommutative Geometry, Trace Formulae and the Zeroes of the Riemann Zeta Function
   Lecture notes by Alain Connes.
   http://www.math.ohio-state.edu/lectures/connes/Connes_course.html

Number Theory
   Proofs along with equation solvers and graphical views written in Java.
   http://www.alpertron.com.ar/NUMBERT.HTM

Number Theory Foundation
   Aims to collect donations from supporters of number theory and to disburse these donations to encourage research.
   http://www.math.uiuc.edu/ntf/

Number Theory Glossary
   Compiled by Robert Campbell.
   http://www.math.umbc.edu/~campbell/NumbThy/Class/Glossary.html

On-Line Encyclopedia of Integer Sequences
   Given an integer sequence, find its name, and formula.
   http://www.research.att.com/~njas/sequences/

Online Seminar: Galois theory of p-Extensions
   Email seminar on "Galoissche Theorie der p-Erweiterungen" by Helmut Koch.
   http://public.csusm.edu/public/fhajir/kochbook.html

Some Highlights of Arithmetic Combinatorics
   Lecture notes and resources on combinatorial number theory by Terence Tao.
   http://www.math.ucla.edu/~tao/254a.1.03w/

Some Number-Theoretical Constants
   Products of rational functions of p over primes, computed by Gerhard Niklasch and Pieter Moree.
   http://www.gn-50uma.de/alula/essays/Moree/Moree.en.shtml

Somos Polynomials
   Related to Somos sequences and elliptic theta functions.
   http://grail.cba.csuohio.edu/~somos/somospol.html

Square-free Gaps
   Algorithm and source code for the calculation of square-free numbers and gaps.
   http://www.marmet.ca/louis/sqfgap/

The Arithmetic Properties of Binomial Coefficients
   Activated text by Andrew Granville.
   http://www.cecm.sfu.ca/organics/papers/granville/index.html

The Somos Sequence Site
   Web resources for information on Somos sequences and related topics such as elliptic divisibility sequences.
   http://www.math.wisc.edu/~propp/somos.html

The Valuation Theory Home Page
   A forum for all mathematicians who work in valuation theory or apply valuation theoretical results in their own field of research.
   http://math.usask.ca/fvk/Valth.html

The Work of Robert Langlands
   Thesis, papers, manuscripts, letters and bibliography.
   http://www.sunsite.ubc.ca/DigitalMathArchive/Langlands/intro.html

Transcendental Numbers
   Maple worksheets, lecture notes and links to other resources by John Cosgrove.
   http://services.spd.dcu.ie/johnbcos/transcendental_numbers.htm

Vignettes on Automorphic and Modular forms, Representations, L-functions, and Number Theory
   By Paul Garrett.
   http://www.math.umn.edu/~garrett/m/v/

Visible Structures in Number Theory
   By Peter Borwein and Loki Jörgenson. Recognising number patterns visually.
   http://www.cecm.sfu.ca/~loki/Papers/Numbers/

World Records for Numerical Palindromes
   The 196 Palindrome Quest and The Most Delayed Palindromic Number, by Jason Doucette.
   http://www.jasondoucette.com/worldrecords.html