Bukkit

This plugin utilises Hidendra's plugin metrics system, which means that the following information is collected and sent to mcstats.org: A unique identifier , The server's version of Java , Whether the server is in offline or online mode , The plugin's version , The server's version , The OS , version/name and architecture, The core count for the CPU, The number of players online, The Metrics version If you wish to disable this feature, you can do so by opt-ing out, which you can do in the config file under /plugins/PluginMetrics/

This plugin has a built-in auto-updater, which connects to BukkitDev to check for updates. If you, for some reason, wish to disable this process, you can do so by setting 'updaternotify' to false in the plugins' settings file.