Reseller hosting, or advanced application hosting.
If you aren't comfortable managing your VPS from a command line then you might consider adding Plesk.
Parallels Plesk is the leading multi-platform control panel designed to provide a simple, convenient way to manage your web services. Using Plesk's intuitive, browser-based interface you can instantly create mail accounts, configure your domain settings, manage your web files, install a site application, create a database, manage your FTP access, and much more.
Plesk simplifies these tasks so that you can accomplish them without having a detailed knowledge of server commands and shell scripts.
Plesk is available for both Windows Server 2003 and most Linux distributions.
For more information on Plesk's key features, please visit Plesk Control Panel Features