Google Gears is a really exciting development and one practical usage is already available. Google Reader can go offline.
Google Gears (BETA) is an open source browser extension that enables web applications to provide offline functionality...
The setup and installation is easy. So now you can use Google Reader on the airplane or the buss and when you go online again information on what you have read will be synchronized.
Images are not available offline though. Hopefully this will be added later on.