This looks like a great tool. I plan on testing it out. I've been used to using SVN to diff changes but I have some websites in Dropbox that I haven't yet put into an SVN repository so this would help a lot.
That's exactly what I use it for. On big projects I use github and tower. But on smaller projects or for just general diffing things in the dropbox this is pretty amazing.
Just for good measure: If you don't want to install an extension to inspect another extension all chrome extensions are just zip files so if you download the extension you can just unzip and see the contents.