This is a sample script that I created to show how you might create a relatively complex virtual farm environment. The hypothetical requirements for this farm are:

1. Add 10 ESX servers to a vCenter, one for each customer
2. Create a resource pool for each customer
3. Inside each of these, create a resource pool for each server role, and a specified number of virtual machines, based on previously-created VM templates
   1. 2 x proxy server
   2. 4 x web server
   3. 2 x app server
   4. 2 x database server

I hope you find the script useful!