So recently I have joined a faction but I am never on at the same time as the other players so I found this http://dev.bukkit.org/bukkit-plugins/lastlog/ -Info about LastLog Pluggin It will help players find out when other players were last on. It can be very helpful in factions. Thnx for taking the time to read this
There already is something like this. Do /seen playername and you'll see when he was last online. Example: /seen RP39. Or, you can do /f show and point at the player's names and it might show when they were last online. I'm not sure if that one still works or not though.