Own made Add-Ons whose status is WIP or being updated regularly. The others aren't discontinued, but sort of since they are stable/mature unless a Fx API change requires updating them.
Get a faster browsing experience by blocking nasty web resources using Bluhell Firewall, the lightweight Ad-Blocker and Tracking/Privacy Protector.
Watch videos anywhere in cinema mode without leaving the website you're on.
Install Browser Extensions straight from GitHub Repositories
Track your Firefox's (about:config) preferences for unwanted changes.