Nabokov Criticism
http://www.libraries.psu.edu/nabokov/forians.htm
A collection of "both original and previously published criticism by some of the best known Nabokov scholars in the world." Extremely useful and interesting.
Nabokov Under Glass
http://www.nypl.org/research/chss/epo/nabokov/
A web version of an exhibition drawn from the Archive at the Henry W. and Albert A. Berg Collection of English and American Literature; it consists of a fascinating array of artifacts from the writer's life with well-researched commentary.
Vladimir Nabokov's Lecture on the Metamorphosis
http://www.fortunecity.com/victorian/vermeer/287/nabokov_s_metamorphosis.htm
An Online copy of Nabokov's lecture on Kafka's "The Metamorphosis"; an excellent introduction to Nabokov's theory of literature and art.