• Javascript (Node/Express)
• Ruby (Rails)
• PHP (Zend Framework 2)
• PHP (Symfony 2)
• Nginx
• Java
• Apache
• ASP.NET MVC
• ASP.NET MVC (another option)
• Python (Tornado)
• Scala (Spray)
• Python (Django)
• Javascript (Node/Koa)
• PHP (Laravel)
• Javascript (Hapi)
• Go
• Yeoman & Static Node Server
• Sails.js
• IIS

I'll keep this list updated as more middleware is added.

Feel free to implement one of the frameworks that people are asking for!

Add a comment if you'd like to see more middleware in another language/framework, and I'll add it to the list!