For the last several months I've been working on a new open source project that I've been calling SynchroEdit. SynchroEdit is a browser-based simultaneous multiuser editor, useful for "same-time" collaboration. The basic concept is that it allows multiple users to WYSIWYG edit a single web-based document, all at exactly the same time. SynchroEdit continuously synchronizes all changes so that users always see the same version. They can also see each others' changes as they type, see where each user is currently editing, and see each others' changes by color.
A blog on social software, collaboration, trust, security, privacy, and internet tools by Christopher Allen.