Take a look at the White House's robots.txt file. This is the file that prevents (well-behaved) search engines and archivers from reading particular files and directories.
I wonder, why don't they want public documents about Iraq to be indexed and archived? A lot of the Iraq-related directories they're blacklisting don't even exist. That seems a bit odd to me.
Addendum: When you see files numbered sequentially, but discover that certain numbers aren't linked on the index page, it's interesting what you can find when you go looking for the missing ones.