ScriptCraft lets you create mods using Javascript. http://github.com/walterhiggins/ScriptCraft/
ScriptCraft is a plugin for Minecraft Servers which lets operators, administrators and plug-in authors customize the game using Javascript. ScriptCraft makes it easier to create your own mods. Mods can be written in Javscript and can use the full CanaryMod API or Bukkit API.
Once ScriptCraft is installed, you can create a new Minecraft mod by adding .js files to the scriptcraft/plugins directory. The following example will add a new 'jsp greet' command to the game:
// scriptcraft/plugins/greet.js
var utils = require('utils');
command(function greet( params, sender){
var recipient = utils.player( params[0] );
echo( recipient, 'Hi ' + recipient.getName() );
}, utils.playerNames);
At the in-game prompt type 'jsp greet <TAB>'. Pressing the TAB key brings up a list of player names. Choose a player and hit enter. The player will receive the message.
