We are currently looking for a developer to write code to allow easy integration of WHMCS (Billing system) with XenServer 5.5. This scope of this project will require PHP and PERL coding to be accomplished.

Essentially we need to be able to indicate a client's PV environment in their WHMCS account, then allow them client to perform Stop, Start and reboot functions using WHMCS. In addition, we need bandwidth accounting for each client PV.

There is a similar module available. However, the vendor does not provide the adequate support or coding to get it to work properly.
WHMCS API: http://wiki.whmcs.com/API
XenServer API/SDK: http://community.citrix.com/cdn/xs/sdks