Some ideas that came to my mind after looking into LISTSERV's console log:
 
* A lot of people try, say, 'SIGNOFF X-L John A. Doe'. When LISTSERV complains
  that only  one argument is allowed,  they try "HELP SIGNOFF".  And this does
  not  work. Maybe  a short  (4-5 lines)  help could  be implemented  for some
  commands (at least for the most commonly used ones). I know that the signoff
  example is a  little stupid, but a)  I have seen lots of  people doing that,
  and b) in other cases the command syntax is not so natural.
 
* A user does  'SELECT * IN X-L',  then 'INDEX'. There were 150  hits, he gets
  the first 30 as output, and then, since  he wants to know more, he notes the
  date of the last  one and does 'SELECT * SINCE date' and  asks for the index
  again. Maybe a 'MORE' option could be added -- it's unclear to me if only to
  the  INDEX  command  or also  to  PRINT.  By  the  way, DATABASE  is  pretty
  underused, at least in my node.
 
* Lots of  users mistake LISTSERV  for NETSERV and  vice-versa, so that  I get
  tons of REGISTERs and SUBSCRIBEs on  NETSERV and the same number of requests
  for NETSERV FILELIST  on LISTSERV. I think that NETSERV  and LISTSERV should
  be mixed, people do  not understand why there are two  servers, and they are
  right.
 
Jose Maria