Another thing you can do that will also work with POST forms that require POST is..

- Grab the source of the page and put it in your favorite HTML editor (DreamWeaver, Notepad, whatever)
- Change the action into an absolute url
- Enter the data you want to submit into the fields
- Note the form tag's name. Give it one if it doesn't have one already (e.g. name="myForm")
- Put onLoad="myForm.submit()" in the body tag
- Save and put the HTML file somewhere.

Now if you load that file (with JS enabled), the form, with the content you've entered in it, is submitted exactly like you were at their site typing it in.