From the product page

Django HTTP Proxy allows you make requests to an external server by requesting them from the main server running your Django application. In addition, it allows you to record the responses to those requests and play them back at any time.

One possible use for this application (actually, the reason it was developed) is to allow for easy development of Ajax applications against a live server environment:

• Avoid typical cross-domain issues while developing an Ajax application based on live data from another server.
• Record responses and play them back at a later time
  • Use "live" data, even when you are developing offline
  • Speedy responses instead of having to wait for a remote server
• Manually edit record responses via the Django admin interface

Combined with the standard Django development server, you have a powerful (but easy to set up) toolbox for developing Ajax applications.