Perhaps the best criticism of the Bell Curve was written before it was published--see writings of Richard Lewontin and Michel Schiff, Albert Jacquard, Elaine and Henry Mensch, Richard M Lerner. For criticism of the factor analytic derivation of g from a battery of intelligence tests, see Stephen Jay Gould's classic Mismeasure of Man; the description and critique of this specific use of factor analysis, otherwise defended as a technique for discovery, is also ably carried out by Davis Baird in Inductive Logic.
For an insightful discussion of how the eugenic vision has always contradicted Darwin's theory, see relevant chapters in Jean Gayon's Darwinism's Struggle for Survival; Gould's recent piece on Sir Ronald Fisher in Dinosaurs in a Haystack is quite interesting as well for the role the eugenic vision played in the foundations of population genetics. For Karl Pearson's brilliant development of empirico-statistical argument to defend the hereditarian position, see the lead article to Stephen Stigler's new book Statistics on the Table (only read it in the bookstore, not yet released to libraries--the Keynesians here should get a kick out of it).
Here are some major academic critiques of the Bell Curve itself(other than those already mentioned): Claude Fischer, et al Inequality by Design; Bernie Devlin, et al Intelligence, Genes and Success: Scientists Respond to the Bell Curve (really liked Burton Singer's and Clark Glymour's contributions); Joel Kincheloe, ed. Measured Lies: The Bell Curve Examined; Ashley Montagu, ed. Race and IQ (the 1999 updated ed. has great contributions by Ned Block and C Loring Brace); Stephen Rose Lifelines (important criticism throughout the text).
This should get one started on this 'interesting' debate that Norm Levitt, science guru, wants to keep alive.
A recent attempt to defend the Bell Curve from such criticism is Max Hocutt and Michael Levin, "The Bell Curve Case for Heredity" in Philosophy of Social Science, vol 29, no 3 Sept 1999 (398-415).
Pleasant dreams.
Rakesh