BSKicker (pun intended) kicks idle players from busy servers to make room for other players. For minecraft 1.2.5, 1.2.4 and 1.2.3.

It was designed from the ground up by MehrCraft/XMdead, a professional Java developer and long-time gamer, to address the needs of Big Servers.

Features

Negligible impact on server load. Among other things, it does not listen to player events because they are resource intensive.
Avoids false-idle kicks.
Flexible configuration.

Installation

Place the JAR file in the server's plugin directory.
When loaded for the first time it will create a BSKicker subfolder that contains config.yml.
Edit config.yml to match your preferences, or leave it as is since it starts you with reasonable settings.
Optionally setup the bsKicker.active permission for your default (true) and exempt (false) player groups. Unlike players, OPs are exempt from kicks by default.

Configuration

log.level: Only changed for debugging purposes if you are having trouble.
task.initialDelayTicks: How many server ticks after the server starts should BSKicker start. You want BSKicker to be one of the last plugins to load. Setup this to a high enough number to ensure it.
task.frequencyTicks: Every how many ticks should BSKicker wake up. Make this number high enough so that it only wakes up a few times between checks. The wake up and go back to sleep process happens in microseconds and causes no load on the server. It is used purely to allow the runs to happen on a "time" basis instead of being dependent on number of ticks.
check.frequencyMinutes: The time between checks. If a player is determined idle by the check, the player's idle count is increased. If the player moved his idle count is reset to 0.
check.maxIdleCount: When a player's idle count reaches this level he is eligible for kicking.
check.minPlayerCount: There is no need to idle kick players on an empty server. Kicking only begins when there are at least these many players on the server. If you want to idle kick on empty servers, simply set this value to 0.
check.idleKickMessage: The message you display to the kicked players. You may customize it to be friendly, humorous, or anything you like.

Future plans

Please note that future features are either not implemented yet or are only partially implemented.
This plugin will eventually implement proactive troubleshooting. Proactive troubleshooting is code that detects when the plugin fails to perform as designed - for example if the idle check tasks take too long to execute or an error is thrown - and notifies the developer of it. This allows the developer to identify plugin problems early and release an updated version... possibly before the server or its users realize that they have a problem. Any plugin support tools implemented as part of proactive troubleshooting are non-intrusive and do not affect the server, other plugins or users. Any troubleshooting support features, like turning on debug messages, will only affect support staff and will never interfere with the server's normal operation. We are confident that these professional-level features will deliver previously unheard-of levels of reliability for server plugins.
Additional features are envisioned for the plugin. This description page will be updated as they get released.

Servers