Mozilla implemented a Social API in the Firefox web browser back in 2012 which allowed social networks to integrate some of their functionality directly into the browser.
First to join was Facebook with its Messenger application and a handful of other providers followed. The api was improved in Firefox 27 adding support for running multiple networks in Firefox, something which was not supported before.
One of the core issues of the feature was that you had to visit a specific site on the developers website, e.g. Facebook, to install the provider in the browser.
This made it quite difficult to discover providers supporting the API among other things.
The Social API provider is installed in a sidebar in the browser that you can display or hide with the click of a button. Depending on the provider, it may display recent activity information, a chat window, or information related to the service such as new music.
Up until now, it was up to the developer to provide Firefox users of its service with access to the social service.
That's probably one of the main reasons why Mozilla has created a directory that lists all Social API providers that are currently available.
Here you find all supporting services listed and can activate them right away without having to visit another page to do so.
A total of eight services are listed on the page currently with Facebook being the big social network that everyone would expect to be found here. There is no Google+, no Twitter, no Instagram, but Pocket, Delicious, Mixi,Sphere, Cliqz, Weibo and Saavn instead.
Please note that Facebook Messenger is not available anymore. All you get is Facebook Share, a tool to share web contents on Facebook. It displays as a single icon instead of a sidebar menu.
To install them, visit the directory and click on the service that you are interested in. Here you find basic information about what it offers and a screenshot that previews how it looks like in the browser.
A click on the activate now button displays a notification at the top about the process. Here you need to click on the enable services button to add it to Firefox.
Depending on your version, it may be displayed in a sidebar right away, or only as an icon in the browser's toolbar that you need to click on to display it.
You can manage all installed services on the about:addons page. Here you need to switch to Services to get a list of all installed providers. Providers can be removed from Firefox again, or disabled instead.
A central location alone won't help unless Mozilla promotes the page actively to its user base. I'm still skeptical when it comes to the feature as I do not really have a use for it. While I'm not a heavy social networking user, being one usually means that you are on the site of the network anyway.
Are you using services in Firefox? If so which and for what purpose?