A couple of services have been drawn to my attention recently that may be of interest to readers of the Weblog and Information Research.
The first is, in effect, a public archive of writings on anything imaginable, from scientific papers to cookery books - it's called Scribd (presumably intended to be pronounced 'scribed'). I haven't explored it to any very great extent at present, but one of the features is that you can point friends and colleagues to documents that you have placed on Scribd - enabling a modest kind of collaboration.
The other is Mendeley a system to "Manage, share and discover research papers". The aim of this system is ambitious and has behind it, apparently some of the people who established Skype - which implies serious money. Mendeley comes in two forms, a desktop system for bibliography management, and a Web system for finding papers, organising your own, and discovering potential collaborators. I shall keep an eye on this one - it has things in common with Zotero, but a whole lot more besides.