Bukquery

Bukquery is one of the few of its kind. It is a rcon tool that allows developers to easily control and query a Bukkit server remotely. It comes with a few built-in commands – however, commands from any plugin can be used (Bukquery emulates the console, therefore it has full permissions and can use any commands the server console can use).

Will Bukquery still be around in 1.9? rcon is coming out!
Possibly. I know that I'll definitely be keeping Bukquery around for my own personal purposes (as I'm far too lazy to update all of my systems that depend on it!).

What commands are available?
Commands from any plugin can be used, provided they can be used from the console.
Bukquery-specific commands can be viewed at the commands page.

What about the configuration options?

See here.

I have made an example program in Java to test Bukquery.
Click here to view it.

For plugin developers
Want to support Bukquery in your plugin, maybe to provide different output when a command is executed via rcon? No problem! Just reference the Bukquery.jar file in your project and see if a CommandSender is an instance of RconCommandSender (com.forairan.bukquery.RconCommandSender). If it is, it's being executed from rcon, so you may want to change the output accordingly.