Justin Tadlock’s ButterBean Metabox Framework
As long as I’ve know about him, I’ve admired the work Justin Tadlock does in the WordPress world. He’s recently released a new framework for rich WordPress metadata editing interaction. Basically, think of something like the WooCommerce or Yoast widget that you see on all products or content on your site. ButterBean is Justin’s solution for making those for himself. And other developers can probably get some mileage from it too.