Gmail Offline is a Chrome Web Store app that’s intended for situations when you need to read, respond to, organize and archive email without an internet connection. […] After you install the Gmail Offline app from the Chrome Web Store, you can continue using Gmail when you lose your connection by clicking the Gmail Offline icon on Chrome’s “new tab” page.
I haven’t had a chance to try this yet but it sounds pretty cool. Also it might just make me use Chrome a lot more than before. You can read all about this on the official Google post.