RESTClient is an application use to visit and test RESTful services.
REST (Representational State Transfer) is the model of the Web to consume web resources. The browser makes a request to a URL and receives a response. The request may be a GET or POST (or a PUT, DELETE, or HEAD) and the response may be anything HTML, Image file, PDF, XML, JSON etc.
Some RESTful Web Services…
http://www.flickr.com/services/api/
http://code.google.com/p/a2zvideoapi/
RESTClient extension: https://addons.mozilla.org/en-US/firefox/addon/9780