Beaglebone: new version of BeagleBoard
beagleboard.org
beagleboard.org
Mine is based around CodeMirror (http://codemirror.net), while they chose Cloud9 (http://c9.io). I actually started using Bespin, which was a precursor to Cloud9, but switched to CodeMirror because it had less kitchen sink included.
The Beagleboard was nice but at $150 - unless you REALLY needed the small size you could buy an old laptop for less and get a screen/keyboard/disk/network/PSU