However I like the Web applications, the fact is that as soon as you do not have connectivity, they are of very little use. Well - maybe not for long. The Dojo Offline Toolkit makes promise that sounds almost too good to be true:

Imagine a version of GMail with a “Work Offline” button on the left-hand side of the screen. When pressed, GMail downloads 100 of your most recent emails into Dojo Offline, including pieces of it’s user-interface. A user can now close their browser and leave the network, stepping on an airplane for example. Once in the air, the user can then simply open their laptop and browser and type in The GMail UI magically appears, along with their 100 most recent emails. A user can read these mails, compose new ones, or reply to existing ones. A flight attendant announces that the plane will land soon; the user closes their browser and laptop. Later, when they are back on the network, they can click the “Work Online” button, which will send all of their locally written emails to the GMail server.

or even for Google Docs:

simply select which documents you want to have locally. Later, open your browser and navigate to, working from anywhere you want, even without a network. When you are done, press the “Sync” button to send it back to the server with your changes when the network reappears.

The technology behind is local proxy with Javascript autoconfiguration and local file cache. It is a project in progress, so unfortunately, you cannot try it out right away :-( - but seems very promising. Best of all, it should be multi platform (Windows, Mac, Linux) and opensource (BSD License).

Cannot wait !