AJAX Testing, Logging, and WSGI Middleware
An architecture astronaut at work:
Now, imagine more than that: Include XSL filtering in a REST API. Transform the plain old XML results of a GET request into a full-on XHTML/CSS/JavaScript browser-based application primed with that data. Include the interactive UI for further drill down queries, as well as forms for submitting edits of the data back to the server via POST/PUT/DELETE using XmlHTTPRequest.