Theme Check plugin
The WordPress Theme Check plugin for Envato
A library of code useful for developing church WordPress themes that use the Church Content plugin.
WordPress options panel for themes and plugins.
A theme support plugin for WordPlate
A robust code template for creating a standards-compliant WordPress plugin.
WordPress Theme for a Twitter archive (to be used with plugin Ozh' Tweet Archiver)
WordPress plugin to get updates for themes and plugins from private GitLab repos — can also be implemented into a plugin or theme.