Paste n' Go 0.1.2
Summary:
Adds an item to your right-click menu for text fields to paste the clipboard contents and submit the form.
Link:
https://addons.mozilla.org/en-US/firefox/addon/paste-n-go/
Description:
Simply right click on a text field and choose "Paste and Go". This will paste the contents of your clipboard into the text field and submits the form.
This extension works on any text box on the current webpage. But it only works on traditional forms. For really fancy webpages that use scripts to submit a form, it might not work. This extension will notify you if those circumstances are detected.
Picture: