I've created a plugin for Vanilla servers that fires off whispered JSON messages based off of in-game events (such as a user logging in or dying) or off of a command execution by a user.
Here is a screenshot after logging into my test world.
Here is a link to the GitHub project. This includes the instructions for installing and configuring the plugin.
I threw together the README pretty quickly, so if you guys have any questions in regard to how it functions, how to set it up, or anything else, please let me know