When Google purchased real-time document collaboration platform EtherPad's parent company Appjet in December, EtherPad's code was made public. EtherPad itself no longer exists, but some similar services have popped-up. Most notable perhaps is TitanPad. TitanPad uses the EtherPad API to provide a free platform for real-time document collaboration.
TitanPad is essentially a clone of the original EtherPad. With TitanPad anyone can instantly create a collaborative document. You do not have to create an account to use TitanPad, in fact creating an account isn't even an option. To get started just click "create public pad," enter your name, and start typing. To invite people to collaborate, just share the url assigned to your TitanPad. Every collaborator on TitanPad is given a unique color to highlight the text they've added. Try it now on this document that I started.
Applications for Education
TitanPad could be used as a platform for quickly hosting and recording an online brainstorming session with your students. As accounts aren't necessary you won't lose any classroom time to getting students through a registration process. Earlier this year Kristen Swanson wrote a guest post for me in which she shared how she used EtherPad and the Week In Rap with her students, read that post here.