You can also look up for these other topics:
Framework
Coding Standards
Boilerplate
CMS
Tool
Security
Hacktoberfest
Eloquent Befriended brings social media-like features like following, blocking and filtering content based on following or blocked models.
renoki-coShare a media library across the WordPress Multisite network
bueltgeA PHP library to deal with all those media services around, parsing their URLs and displaying their audios/videos.
dereuromark