The Google Mashup Editor is a tool that enables you to create AJAX-based applications. You can pull data from external RSS and Atom feeds as well as Google Base. Additionally, you can write to application- or user-specific feeds.
GME provides versatile modules through declarative XML tags. When used in conjunction with HTML, CSS and JavaScript, these tags allow you to create web applications and mashups quickly and easily. GME also takes care of the storage, hosting and serving of your web application.
To get started using GME, please go to http://editor.googlemashups.com.