Act-as-Buddy is a gem to allow any model to implement self relation. For eg: the friendships of a user can be implemented easily by self relation technique of act_as_buddy. Any Model can be buddied or lopped on to itself. Main uses would be for Users create friends etc.. Eg: User has many friends...

Ping.fm (http://ping.fm) is a simple service that makes updating your social networks a snap, and this it's Ruby library.

Check how many times a URL has been shared on social networks and aggregators

Check social networks for username, and find out is it taken. Option to run in 'hunt' mode, to confirm registered users across the networks.

Give this ruby gem a URL, it will give you back how many times it's been shared / liked across various social networks.

== DESCRIPTION: Blackbook automates the nitty-gritty of importing contacts from various services and files and exporting them as VCard, XML, or simple Hash. Utilize those contacts from services like AOL, GMail, Yahoo Mail, Hotmail or CSV to help your social networking site become GIGANTIC overni...

Simplify the definition and storage of "network" relationships, especially useful for social networks.

Map social networking sites' URLs to and from a canonical form.

DeliveryGuy will be happy to help when you need to spread your RSS feed to social networks

Massive-scale social network analysis. Nothing to f with.

Get page statistics from the most popular social networks.

Gigya's gem is a lightweight library to connect for multiple social networks using Gigya's REST API. It allows read/write access REST API, as well as support for OAuth.

Abstract classes for Fetcher Microdata serialization of social network data

A Bunto plugin to add metadata tags for search engines and social networks to better index and display your site's content.

HelloTxt (http://hellotxt.com) is a simple service that makes updating your social networks a snap, and this is it's Ruby library.

A command line interface to The Grid: Social Networking, Web 0.2

A ruby gem providing social networking features for rails app.

Distributed & Decentralised Social Networking

Fetches the count of likes for specified URL in social networks

Generic social network notifications.