In the good ole
days of dialup BBSing
(insert nostalgic sigh here)
A Co-SysOp was that user (or two) who kissed just enough SysOpButt to earn the right to have a smidget of control of the system. On rare occasions, a Co-SysOp could be found that was actually an equal partner in running the BBS. This was usually the result of sharing the costs of additional hardware and phone lines, much to the dismay of the broke 16 year old who's box the BBS was running on.
That lucky soul (or few) oftentimes earned the great privilege of running up their parent's phone bill making calls to complete strangers to verify that they do indeed exist at the phone number they provided in their initial account information. Interestingly enough, this is how I met the love of my life (thus far). And, for the *cough* 1337 mis0gynists, *I* was the Co-SysOp, and darnit, I was hardcore. w00t! (i'm really not trying to prove anything here...
The more interesting *snicker* tasks included message board creation and moderation, user questions and concerns, and file board maintenance. Not that a Co-SysOp could (or would) read private messages between other users. That would be unethical.