Gears is an open source project that enables more powerful web applications, by adding new features to your web browser:
Gears is a plug-in that extends your browser to create a richer platform for web applications. For example, webmasters can use Gears on their websites to let users access information offline or provide you with content based on your geographical location.
Desktop
Let web applications interact naturally with your desktop.
Database
Store data locally in a fully-searchable database.
WorkerPool
Run JavaScript in the background to improve performance.
For Windows XP/Vista. Firefox 1.5+ and Internet Explorer 6.0+