Chromeless is a Chrome web browser without the chrome.
Kinda like Fluid, but faster to configure. Just install the extension and every time you launch it you'll get a new window.
git clone this repo. Go to Chrome Settings > Extensions (chrome://extensions). Choose "Load unpacked extension" and choose the unpacked-extension folder in this repo.
I'll put this on the Chrome Web Store as soon as Google makes that available. See Chrome Packaged App Publishing for more information.