Sites

The LLL Algorithm (Popularity: )
http://www.dice.ucl.ac.be/~fkoeune/LLL.html
Papers on the LLL algorithm and its applications collected by François Koeune.

Visible Euclidean Algorithm (Popularity: )
http://www.math.umn.edu/~garrett/crypto/a01/Euclid.html
Enter two positive integers, and click the button to see the operations of the Euclidean Algorithm.

Basics of Computational Number Theory (Popularity: )
http://www.math.umbc.edu/~campbell/NumbThy/Class/BasicNumbThy.html
Notes and Javascript illustrations by Robert Campbell.

LLL Page (Popularity: )
http://www.numbertheory.org/lll.html
Maintained by Keith Matthews. Papers, examples, pseudocode.

Algorithm Design Manual - Number Theoretic Algorithms (Popularity: )
http://www.cs.sunysb.edu/~algorith/major_section/1.2.shtml
A chapter from "The Algorithm Design Manual" by Steven S. Skiena.

Implementations of Extended LLL (Popularity: )
http://www.math.uu.nl/people/vdkallen/lllimplementations.html
Links and notes by Wilberd van der Kallen.

Suggested Readings in Algorithmic Number Theory (Popularity: )
http://www.msri.org/local/library/reading_lists/0001-ant.html
Provided by the organizers of the MSRI Fall 2000 research program.

Computational Projects in Number Theory (Popularity: )
http://www.ieeta.pt/~tos/hobbies.html
Interesting problems, usually requiring extensive verifications or enumerations, to occupy the idle CPU time of workstations and personal computers. Compiled by Tomás Oliveira e Silva.

Future Directions in Algorithmic Number Theory (Popularity: )
http://aimath.org/WWN/primesinp/
Some of the conjectures and open problems motivated by the "PRIMES is in P" papers, compiled at the AIM.

Computational Number Theory (Popularity: )
http://www.math.umbc.edu/~campbell/NumbThy/Class/
Lecture notes by Robert Campbell, December 1997.