Best 40 Free Downloadable Social Networking Platform  

This is Vivalogo's list of best free, downloadable, open source social networking software (kinda hard to say all these words :) ).
Unlike some other lists you may find on the net, this one contains only really downloadable and functional software.
Note: listed in no particular order.

spree

spree is an expert search engine where users ask questions to find other participating users, who are knowledgeable in that area and willing to help.

iSocial

iSocial is a free social networking CMS software that allows you to create your own Friendster and Orkut like sites. Use bookmarks, dating and create groups with just one mouse click.

Mahara

Mahara is fully featured electronic portfolio, weblog, resume builder, and social networking system for connecting users and creating online communities.

Yogurt

This is a Social Network module for xoops CMS. You have seen Facebook, Orkut, Myspace , try Yogurt for Xoops!

VMukti

VMukti is a Unified Social Collaborative conferencing engine. Allows access through personalized, mashable web-interface. Core features:- Video conferencing, Audio conferencing, IP Telephony, Desktop sharing, Chat, Whiteboard, Presentation & More.

The PeopleAggregator

The PeopleAggregator is a next-generation social networking system that goes beyond the idea of social networks as mating games, and attempts to use open standards, network inter-connectivity and massive flexibility.

Appleseed

Appleseed is (augmented) social networking software, ie Friendster, only distributed. Sites running Appleseed will interoperate, and form the 'Appleseed Social Network.' Development is focused on privacy and security, as well as ease of configuration.

Mugshot Project

The Mugshot site lets you track what your friends are doing online across a variety of popular web sites � music, photos, blog posts, and more.

GetBoo

Web 2.0 bookmarking system, both social (with tags) and private (with folders). Import and export your bookmarks from Firefox, IE, Mozilla, Netscape. Admin management section, translations, groups, bookmarklets, Firefox extension, RSS feeds, and more!

Akarru

Akarru is a social bookmarking engine, is used to build social bookmarkings sites, like www.blogmemes.com. Users posts links and promote links to front page using voting system.

Scuttle

Web-based social bookmarking system. Allows multiple users to store, share and tag their favourite links online.

SemanticScuttle

SemanticScuttle is a social bookmarking tool (based on Scuttle) experimenting new features as hierarchical tags, collaborative descriptions or OpenID authentification.

AROUNDMe

Create collaborative social websites (like Ning, Myspace, Yahoo or Google groups). Each group can create a multiple web pages. They get a drop in guestbook, blog, forum and wiki. Each group is fully customizable using xHTML, CSS, Javascript and PHP.

Clonesumating

Clonesumating is the open source version of the code that runs CONSUMATING.COM. It features many state of the art social networking functions including user profiles, user tagging, matching and discovery based on quirky tag combinations, group activities such as weekly photo contests and blog questions, an event calendar, RSS feeds for everything, etc. It is written primarily in mod_perl.

BeWelcome Rox

Get to know the global village and other cultures, share your place. BW Rox is the platform driving www.bewelcome.org and other social networks, aiming to bring people together in real life. Organize your travel or stay abroad, travelblog, meetings, ...

ICEcore

ICEcore open team collaboration software uses social networking to unify team workspaces w/ real-time web conferencing. Collaboration for knowledge networking, program management, communities-of-practice, telework, ...

Memephage

Memephage is an automated web log (blog). It passively gathers and summarizes links from various places. Currently: IRC, social MUDs, e-mail, and web browsers. Uses the POE multitasking and networking framework for Perl.

InteractOLE

A platform for the delivery and support of online learning. It differs from many other elearning platforms in that its aim is to concentrate on the social/interactive aspects of teaching and learning rather than the delivery of content to students.

Elgg

Elgg is an open source social networking platform developed for LAMP (Linux, Apache, MySQL, PHP) which encompasses weblogging, file storage, RSS aggregation, personal profiles, FOAF functionality and more.

CommunityNews

CommunityNews uses social bookmarking and bayesian techinques to provide periodic postings to blogs. Users can vote for or against RSS sources ti increase the chances that the source is used again. Spam filtering (bayesian) is provided by spam bayes.

OpenPNE

OpenPNE is a Social Networking Service Engine written in PHP. It has many features(friend control,friend invitation,diary,blog feeds,message box,etc).

MonkeyChow

Feed Aggregator Reader (branched from FeedOnFeeds) with Social Bookmarks (del.icio.us, Blogger, Newsvine, Technorati, mailto), Article Starring, Feed Tagging, OPML, Article Search, Reblogging and Refeeding, Aging, and Edit feed attributes.

NewsCloud

NewsCloud is an open source media platform for citizen journalism and the social news network hosted at NewsCloud.com.

Feed Me Links

Feed Me Links stores your bookmarks online so you can get to them anywhere. Import your favorites and share your links with friends. Add tags to organize your links. Discover new things.

WorldSpace

WorldSpace is a user-extensible shared virtual environment, aimed at being a next-generation social networking system.

Social Networking POC

A networking site on the lines of Orkut.Right now we plan to build it on Jboss seam and use a Java content management system like apache Jackrabbit as the backend. It would be more of a POC than an actual commercial app.

Zoints

Zoints is intimately aware that online communities are the most important aspect of the internet. Our free software solutions are designed to help solve the three major problems forum owners face: Member acquisition, Member retention and Profitability.

earth-life-simulation

A simulation of the world, there will be a global map representation and players can choose a country or civilization and develop it's social, political and military existence.

PHPizabi

PHPizabi is one of the most powerful social networking platforms on the planet. With literally thousands of websites powered by PHPizabi including everything from simple friends sites to the most complex networking super sites out there.

Ozcode

Ozcode is the source code behind Ozmozr.com, a microformat-aware RSS aggregator, social networking, resource sharing, identity aggregation and presentation site.

TallStreet

TallStreet.com is a new search engine concept where users make investments, with fictional money, in their favourite websites and the rankings are determined entirely by the users.

Jamss

Jamss is a social news site based off of Digg.com. Jamss allows for peer submission and review of web articles and can be adapted to fit a variety of themes. Jamss runs on PHP/MySQL.

Dolphin

Dolphin is open-source and free, although there is a cost associated with removing the company�s links from your site.

Ospo

Ospo is an opensource social portal project. It use standard function (add, remove friends, top10), forums integration, music module (artists directory with albums, songs), shoutcast integration, blog (add, delete, modify, view) and so on.

AstroSPACES

AstroSPACES is the world's first open source social networking solution. Coded from scratch, it is highly efficient and very easy to use.

FlightFeather

FlightFeather's goal is "social networking for everyone". This means that anyone should have a chance to run a popular social networking site -- on minimal hardware, and without wasting bandwidth.

SNOSS

Social Networking Open Source Software, an open source social networking framework, written in PHP, Javascript and MySQL with an AJAX UI.

OpenSocialNetwork

OpenSocialNetwork is a social network of open source. Its main task is to create a social network releasing the source code.

S3B

S3B - Social Semantic Search and Browsing - is a middleware that delivers a set of search and browsing components that can be used in J2EE web applications to deliver user-oriented features based on semantic descriptions and social networking.

Facelift

Facelift is a visualization and analysis software for online social networking services. It displays a given community as a node-link diagram and provides several search / filtering functions as well as cluster analysis features.