Google has released an early beta of their Gears offline browser extension. With Gears, a developer can make their web application available to users that are not connected to the internet. To accomplish this, the Gears browser extension includes its own database and server for local data storage and retrieval.
If you want to take Gears for a test drive, install Gears and fire up Google Reader. With Gears installed in your browser, you will get an alert when Google Reader loads telling you that the application wants to store some data on your local machine. If you allow this, there will be an additional option in the reader application that switches between online and offline mode. Switching between modes will sync up your local data with the server. In the case of Google Reader, changes to data such as marking an article as read will be carried over to the server when switching back to online mode.
Google Gears currently works with Firefox 1.5 and higher on Mac, Linux and Windows. Internet Explorer is also supported on Windows. Safari will be supported in a future release.
via Calendar Swamp