Lifehacker has a great article on how to use Google Gears to access your Google Reader feeds offline.
What is Google Gears:
Google Gears (BETA) is an open source browser extension that enables web applications to provide offline functionality using following JavaScript APIs:
- Store and serve application resources locally
- Store data locally in a fully-searchable relational database
- Run asynchronous Javascript to improve application responsiveness
Google Gears (BETA) is available for Windows, Mac, and Linux.

