Number Theory - WolframMathworld - Number Theory. 

http://mathworld.wolfram.com/topics/NumberTheory.html

The Valuation Theory - This home page is intended to be 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

MathPages: Number Theory - Number Theory.

http://www.mathpages.com/home/inumber.htm

Number Theory Web 

http://www.numbertheory.org/ntw/

Number Theory - Quadratic two integer variable equation solver, quadratic modular equations, sum of powers.

http://www.alpertron.com.ar/NUMBERT.HTM

Visible Structures in Number Theory - Visible Structures in Number Theory.

http://www.cecm.sfu.ca/~loki/Papers/Numbers/

Active Elementary Number Theory - transformations of relatively prime pairs, representation as sum of two squares, divisors of n*n+1.

http://www.faust.fr.bw.schule.de/mhb/taupaeng.htm

Some Number-Theoretical Constants - Some number-theoretical constantsarising as products of rational functions of p over primes.

http://www.gn-50uma.de/alula/essays/Moree/Moree.en.shtml

Number Theory Glossary - Number Theory Glossary.

http://www.math.umbc.edu/~campbell/NumbThy/Class/Glossary.html

Fermat's Little Theorem - Fermat's Little Theorem.

http://www.pballew.net/FermLit.html