A really detailed and beautiful site is Michael Declan Dunn's Cybrary of the Holocaust.
The United States Holocaust Museum - America’s national institution for the documentation, study, and interpretation of Holocaust history, and serves as this country’s memorial to the millions of people murdered during the Holocaust.
Reader Ari Frankel notified me about a Primo Levi interview on his Web pages.
There is now an official Anne Frank web site. However, I'm potentially uncomfortable with the Anne Frank museum, which runs it. A year ago, a really great unofficial Anne Frank website was driven off the air by copyright threats, and I think--but do not know--that these are the folks who did it. If so, they may be running this a bit too much as a business.
David's Holocaust Awareness Project was compiled by an 11 year old boy.
Brave New Web hosts IDEA, a Webzine dedicated to studying genocide, autocracy and abuse of power. A collection of contemporary photographs of Auschwitz is available here as well.