Several open-source projects of Web2.0

Diggclone-open-source Digg class Program
Official: Http://www.talkingpixels.org/diggclone/index.php
Demo: similar to digg.com

Aroundme-open-source Social Network Program
Official:Https://savannah.nongnu.org/projects/aroundme/
Demo:Http://www.barnraiser.org/demos/
(Social network programs are usually charged. I believe this is the only free social netwokr project currently)

Lilina-open-source RSS aggregator
Official:Http://lilina.sourceforge.net/
Demo:Http://www.chedong.com/

Gregarius-open-source RSS aggregation Program
Demo:Http://rss.gregarius.net/
Official:Http://gregarius.net/
Plugin:Http://plugins.gregarius.net/
Style:Http://themes.gregarius.net/
Forum:Http://forums.gregarius.net/
Help:Http://wiki.gregarius.net/

SA. Bros. US-Open Source Network bookmarks (PHP)
Official:Https://sourceforge.net/projects/sabrosus/
Demonstration in Chinese:Http://www.sluke.cn/demo/monousuario/

Freedmarks-Open Source Network bookmarks (ASP) (China)
Official:Http://www.purewhite.cn/
Demo:Http://www.freedmarks.com/

Scuttle-Open Source Network bookmarks (PHP)
Official:Http://sourceforge.net/projects/scuttle
Demo:Http://scuttle.org/

Yogurt-open-source Social Network Portal
Official:Http://yogurt.sourceforge.net/

Eyeos --- open-source WebOS,
Official:Http://www.eyeos.org
Demo:Http://www.earn8.net
There is a Chinese version.