EtherPad Alternatives

I was talking w/an English teacher last week about Etherpad and did a demo w/my yearbook kids. Great tool, but going away, right?
Fortunately, I put a call out for help to my Twitter peeps and got a number of responses w/alternatives:
Also told about a Wikipedia article w/more options: @ptruchon send me the Wikipedia article mentioned above, but it has changed (not for the better) since sending it.  He suggests this substitute:

Gotta love Twitter!

More to add?  Lesson ideas for using it?