Google Docs. Tungle.me. YouSendIt: Online File Sharing and collaboration with FTP Replac. Enterprise Social Software | Wikis, Microblogging & Feeds - Cube. Teambox | Project collaboration. WizeHive. IdeaScale. Cl1p.net.
Wiggio - Makes it easy to work in groups. ManyMoon. YourDraft.com - Online sharable WYSIWYG document drafting and ed. Untitled. EtherPad: Realtime Collaborative Text Editing.