a box that anyone can edit

Hello im looking for a plugin for my site that i can put on my sidebar or in a page.

what i need is something that would work like notes, i could write in some text and then someone else could do the same from there computer and edit what i wrote.

nobody should need to register or login to use this just a box that everybody can write into and save it and someone else could edit it or add some text to it.

i hope you understand me im not the best in english 🙂