I use DISA.mil for much of my guidance while testing systems and analyzing data from testing trips. It appears that DISA.mil is down. I noticed it yesterday while looking for STIGs, and now SANS has a post on it. The comments allude to a web server being down in the SAN.
Here's the SANS post.
I'll try to post again when it is back up.
Edit (11/17/2011): As of 8:30 this morning, the site is still down.
Edit (11/18/2011): Parts of the site appear to be back up, but in limited capacity.