Palaround - Meet people you should be friends with.
Zotero - Zotero is a free, easy-to-use tool to help you collect, organize, cite, and share research.
Digg - Digg delivers the most interesting and talked-about stories on the Web right now.
Qiqqa - Qiqqa is a free research and reference management software. It can be used in many organizational projects from the academic to the personal to the business endeavor. Read more about Qiqqa.
quippd - quippd is a social news site that anyone can edit.
JabRef - Graphical Java application for managing bibtex (. bib) databases.JabRef · JabRef Help · JabRef | Blog · OpenOffice/LibreOffice .