Installerific
Portable FTP
Creating a PortableApps.com Installer > Portable FTP

Installerific allows you to automatically upload your portable application and the auto update file after it is built.  Both the *.paf.zip and the *AutoUpdate.txt are automatically created as part of the build process.  When your application is launched it will automatically check to see if there is a new version by downloading the AutoUpdate.txt file and comparing it with the installed version.