My zealous employer is now blocking pobox.com because it is "webmail."
Other blocked gems include the journal of Quinn Lester and the homepage of a little cabin in East Texas my wife wanted us to vacation to sometime. Both are apparently "pornography."
Strangely, archive.org is now unblocked, but bugmenot.com has been clamped down upon because it is in category "Criminal Skills."
groups.google.com has been blocked and unblocked many times in the last two years. It is finally blocked now as "usenet news."