PosterPoster
A developer tool for interacting with web services and other web resources that lets you make HTTP requests, set the entity body, and content type. This allows you to interact with web services and inspect the results.
After you install it, just go to Tools->Poster to open the poster window. After that, try a GET or POST on your favorite web service or site.
You may also open Poster using the icon button in the status bar or by a key stroke (see the menu item).
The code is available from http://code.google.com/p/poster-extension/
PLEASE: If you find a bug, file an issue on the project page above.