Connotea is a site for scientists like del.icio.us [1]. You can share references or keep them private on Connotea.

From the site:

``This is Connotea, a free online reference management service for scientists created by Nature Publishing Group. Login or register to get started.

``Connotea helps you store your reference list online, which means that it's readily accessible, it's linked directly into the literature and it's easily shared with your colleagues. Opening your references to other researchers enables you to discover new leads by connecting to the collections of those with similar interests to you.''

URL

http://www.connotea.org

Reference:
1. http://del.icio.us