The Franz Kafka Discussion Deck:
http://westerncanon.com/cgibin/lecture/FranzKafkahall/shakespeare1.html
A good source for random thoughts about Kafka that people have put down here, with a focus on The Metamorphosis.
Don't miss this site:
http://victorian.fortunecity.com/vermeer/287/nabokov_s_metamorphosis.htm
It's a lecture on The Metamorphosis by Vladimir Nabokov, author of Lolita.
Kafka and Jewish Mysticism:
http://member.aol.com/kafka100/kafkakabbalah.htm
This site has an interesting long paper on the relation between Kafka and the Kabbala, the key text of Jewish mysticism. Site also includes a link to the complete text of the Metamorphosis. (You may have to scroll down a bit to get past some empty space put there by poor html skills.)
Leni's Kafka Site:
http://victorian.fortunecity.com/vermeer/287/index.html
Admittedly, this site is a little strange, but it¹s well worth checking out. Random essays and information on Kafka, his books, his Judaism, etc etc.
Constructing Franz Kafka:
http://info.pitt.edu/~kafka/intro.html
An academic site that includes information about Kafka and his works. This site is pretty small right now, but looks like they are going to be expanding it steadily.
Metamorphosis: A New Kafka
http://www10.nytimes.com/books/98/07/19/specials/kafka.html
This site contains Real Audio recordings of a discussion forum on Kafka. The speeches contain some information of interest.