FireFTP Extension

an FTP extension for Portable Firefox

The FireFTP Extension works within Portable Firefox and gives you access to a lightweight FTP client using much of the built-in functionality of Firefox. It includes SSL/TLS support, file diffs, image thumbnails, resumes, proxy support and more. And, since it uses Firefox for many of its functions, it's a very small download.

Extension Homepage: http://fireftp.mozdev.org/