To create bootable ubuntu server 12.10 usb drive installer in ubuntu desktop very easy, for this tutorial we will use Unetbootin. Unetbootin (Universal Netboot Installer abbreviation) is a program that runs on Windows or Linux, and can create USB Installation Linux distributions ( such us ubuntu, debian, linuxmint, fedora etc ).
Unmount and format usb flash drive using Gparted
Open gparted, select USB flash drive
Unmount USB flash drive
Format USB flash drive to filesystem FAT32
if no action, apply all operation from menu Edit -> Apply all operations. close Gparted
Install unetbootin using personal packge archieve (PPA)
sudo apt-add-repository ppa:gezakovacs/ppa
sudo apt-get update
sudo apt-get install unetbootin
Launch Unetbootin (require root authentication), select the Ubuntu Server 12.10 ISO image previously downloaded to the hard disk, Check the installation destination is your USB Flash Drive. Click OK to start copying all file required for installer to USB Flash drive
Besides Unetbootin, in ubuntu there are a few app that can use for creating ubuntu server bootable on usb drive such as (start up disk creator and multisystem).
If you want to create bootable installer Ubuntu Server usb drive in Windows 7, you need to download universal usb installer App. launch Universal USB Installer, Browse and select Ubuntu Server 12.10 ISO image Installer and follow the onscreen instructions.
Now, you have ubuntu server 12.10 installer on USB stick. To install ubuntu server 12.10 from usb stick, plug in your usb stick to your computer and boot from USB drive. Read the Ubuntu Server 12.10 Installation instructions.