Live USB Creator is one such tool which lets you install various cross platform operating system on USB Flash Drives.
This tool has been initially tested to install Fedora on USB Flash Drive, but it can also let you install Windows XP one day on your USB Pen Drive for which research is going on 🙂
Right now it can help you install fedora linux either from a disc image, dvd or you can also download and install fedora on the go.
It will automatically detect all the USB drives connected to your computer on which Fedora Linux or Sugar Spin can be installed.