LiveMinutes is a very cool app that integrates with Evernote (my all time favorite and most used app) and allows you to work on the same Evernote note with others, similar to Google Docs.
Evernote is an excellent app, with the ability to share notes with others, but there is not a collaboration piece until this app came along.
You go to LiveMinutes and create a work space and select the notes from your Evernote account that you want to collaborate on, share them with others and off you go. You see multiple users editing the same note. Even if someone edits the note in Evernote, the changes are synced.
Here's a video that shows how this works: http://youtu.be/FOxYa8NqRmc
If you use Evernote, this is something to look into.