I just dealt with this last night! I wanted to view the pages being served by my dev box (which is on a lan and so has a private IP address and no "real" hostname) on another computer in the LAN. I figured I could just hit AOLserver by IP address, but AOLserver wants to redirect you to whatever it thinks $hostname should be, which is a problem if you don't have any DNS for that hostname! It seems to me that the "out of the box" nsd.tcl file should probably NOT grab hostname from the machine, since the user's first attempt to configure openACS will almost certainly be on a dev box, which may or may not have a real host name.
Alternately, I think that the nsd.tcl needs a comment describing AOLserver's desire to redirect any requests to whatever hostname is. AOLserver's behavior in the presence of an incorrectly set hostname is funky enough that it isn't obvious what needs to be fixed, only that SOMETHING is broken.
