Slingshot allows Rails developers to easily create a hybrid Web/desktop applications.

Joyent Slingshot is a simple and lightweight mechanism to cleanly synchronize online and offline data. You, as a developer, can provide an ActiveRecord transport layer allowing easy customization of the data that gets synced to your application’s who, and when, and how. With the addition of about thirty lines of code, your Rails application can sync data from client to server. With another thirty lines of code you synchronize have file-based data.

Joyent Slingshot allows developers to deploy Rails applications that work the same online and offline (with synchronization) and with drag into and out of the application just like a standard desktop application.