From tessel.io:

Tessel is a microcontroller that runs JavaScript. It's Node-compatible and ships with Wifi built in. Use it to easily make physical devices that connect to the web.

• Programmable via JavaScript
• 14 different hardware modules for added capabilities
• Compatible with 10,000's of Node.js packages on NPM
• Deploy over USB or remotely by WiFi

• 180mhz ARM Cortex-M3 LPC1830
• 32mb SDRAM
• 32mb Flash
• TI CC3000 WiFi radio
• 20-pin GPIO bank for general prototyping
• Micro USB or battery power

Starting at $99 (controller and one module)