The aim would be to have the server track information a player learns about monsters (by reading, by killing repeatedly, things like that). This information could be given to player in due time. Random ideas:
when player knows hp of a monster, display an estimated status bar on a monster - like auto-estimated from done damage
display estimated resistances (through some colors?)
keep known map information
have some means to exchange/sell information between players
have the information decay in time / randomly get altered, to simulate forgetting
have the player carry a book that gets bigger and bigger as time goes by
there was a talk about that (IRC?), paste info here!