That is so cool :). I just slapped together a (really) simple chrome ext for opening up a new tab in "contenteditable" mode. It saves the contents into localStorage, thats it for now :) Here it is if anyones interested https://github.com/jwaterfaucett/textpad
I forked your code, added support so you can do (C-N) to open a new tab, click tab and start typing (the cursor will be at the end of the line), polished it up a bit (changed font to consolas, added a grey background with a tint of white text-shadow). I've sent a pull request.