Tigermouse is a framework for development of highly interactive web applications in MVC architecture. It utilizes AJAX technology extensively and pays attention to be lightweight for low latency and high responsiveness. The most important design principle of Tigermouse is to be ready for enterprise grade, the other just follows this requirement:

• Most processing (esp. business logic processing, e.g. validation) takes its place at the server side. Processing data at client side is jest nothing more than asking for trouble. At the server side you are in charge with your application, at client side you just think you are.
• Be lightweight. Essential when there is a congestion of AJAX calls for server side processing. There is no function or method registering or interface exposing to Javascript.
• Be strictly MVC compliant. It is well tested architecture, also it helps keeping processing code and view code separated.
• No Javascript mess! All Javascript code must be encapsulated at server side (e.g. IReadableView) or client side
• No XML configuration files. Well, actually no configuration at all.
• Be data source independent.

There is a good comparison between Tigermouse and other AJAX frameworks for PHP that you might check it also to see how Tigermouse differs from others.