
Libelula Logger is with no doubt the most effective anti-griefing tool you've ever seen. I believe you should not realize that a plugin is running until you need to use it, and this is a good example of my belief. You'll love this plugin!
For it I have created a specific embedded DB engine called MEODE (Minecraft Event Oriented Database Engine) which allows this plugin to be extremely efficient. Libelula Logger is lagless and uses much less resources than the most general purpose plugins you're probably already using. MEODE can record 61680 events in just 1 MB of hard disk and registers 1800* block break/place events in the same single game tic, undoubtedly much more than what your players can generate.
(*) Tested in a server which supports up to 200 users. (I bet it will perform better with better hardware, anyway it can process much more event than the players of your server can create).
Libelula Logger is a Great pluging, user-friendly, intuitive and very easy to use just like all Libelula plugins. Once installed it starts running with the default configuration and each time a player places or removes a block the event is registered by MEODE and nobody realizes it. When you find a construction/destruction made by a griefer you will be able to:
Libelula Logger will tell you who, when and which. That's all, effective clear and simple.
See Commands and permissions page for a detailed information.
Place the downloaded LibelulaLogger.jar file into your plugins directory and then run (or restart) the server. You also can use plugman (which is an incredible plugin) for loading it without restarting your server.
Libelula Logger is a ready-to-use plugin, you really don't need to change anything on the configuration. Anyway, you probably want to adjust the event registering behavior to your server gameplay. Due to this I made the plugin completely flexible and configurable. All settings can be changed from console or gameplay commands.
Also there is a config.yml you can edit and reload if you prefer.
See all configuration keys description here.
As Professional of Software Quality Assurance I am, I can not risk my own reputation by building buggy plugins. This is a piece of software engineering and best practices which has been properly tested. But all non-trivial software has bugs. Yes, it's true! Seriously it is!!! So let me know if you find any bug and I will fix it as soon as possible.
This plugin doesn't have any dependency.
I created this plugin because there was no one like it, all others plugins I tested which tries to provide this functionality are very slow, overload the server, use external databases and require complicated configurations. This lightweight plugin is exactly what I looking for but I cannot convert it in a great plugin by myself. I need your help and a good way to help me is by creating tickets for new features, ideas and bugs (if you find them). For my part I commit to classify and develop all these ideas as have time to do it.
Another very good way to support this plugin is by doing a tiny donation, a few cents will be enough for let me know that my work is useful for somebody else.
The software is Beta again so I started working in the Import/Export tool with the following possible features:
It would be great if you could help me work in the wee hours of the morning:

Libelula Logger is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
Please read about GPL License here