Multiplicities of Discriminants - Formulae and tables for the number of non isomorphic fields with a fixed signature and Galois group sharing a common discriminant. - http://www.algebra.at/multi.htm
Algebraic Number Theory - A course by Keith Matthews. Lecture notes (GIF slides), bibliography, web resources. - http://www.numbertheory.org/courses/MP473/
Quadratic Fields Research - Notes by Richard Mollin. - http://www.math.ucalgary.ca/~ramollin/research2.html
Discriminant Exponent Calculator - Java applet computing the maximum exponent of a prime in the discriminant of a number field of given degree. - http://www.public.asu.edu/~jjones/java/discrimexpo.html