EtherPad is a great easy-to-use tool for simple, real-time collaboration of text documents. Multiple people can edit the same document simultaneously with any changes instantly reflected on everyone's screen.
On 4 December 2009, it was announced that AppJet Inc. (the parent of EtherPad) had been acquired by Google and the EtherPad team would continue its work on realtime collaboration by joining the Google Wave team.
Because of strong reaction to this news, on 5 December 2009, Aaron Iba (former CEO of AppJet) announced that pad creation from the EtherPad home page would be re-enabled and would be maintained at least until the code had been open sourced.
On 17 December 2009, the EtherPad source code was released. This has resulted in the birth of several EtherPad clones on the web. As you can see from the screenshots which follow, these clones have been faithful to the original EtherPad concept, one to the point of not even changing the name in the title bar.
The original EtherPad
In so far as I can tell, there is no functional difference among these. Pick anyone you like to get the EtherPad experience. If you discover anthing unique to any one of these, please add it to the comments.
You can even get directions for running your own etherpad server here.
DISCLOSURE OF MATERIAL CONNECTION: http://cmp.ly/0