While some of these might be plugins or themes, they are all designed to be customized and used specifically by developers.
» Custom Metaboxes and Fields for WordPress
This is a code library that can be used by themes and plugins to easily generate metaboxes – areas inside the Edit Post screen that allows you to collect additional data about the post.
It started as a part of the TwentyTen CRM theme I built with Jared Atchison and Andrew Norcoss. But once we built it, we found that we used it on almost every client project since. It’s now hosted on Github where we actively maintain it, creating and accepting patches for bug fixes and enhancements from the community.
» BE Genesis Child
This is the base child theme that I build all my client’s sites from. It’s real basic but it has the code organized in the way I like, and it has code I use often (like unregistering certain layout options).
» Core Functionality plugin
As described in this post, the core functionality of a website belongs in plugins, not a theme. When the client changes themes in a few years, they will want the features their depends on to still work.
This is the base plugin I use on all projects for general functionality (registering post types, creating metaboxes…). If there’s a very specific feature that the client might want to selectively disable, like an Events Manager, I recommend putting that in its own plugin.
