DayZ Server Monitor lets you view the current player count on any running DayZ server. By default, your current/last played server is shown.
The player information updates once per minute and whenever you change servers. DayZ Server Monitor determines your current/last played server by reading your DayZ profile file, so it needs to run on the same computer that runs the game.
More information is available at https://tjensen.github.io/DayZServerMonitor/