I am currently setting up some servers that I want users to be able to log into a site and do basic commands on their VMs. Does anyone know of one besides paying VMWare huge amounts of money?
Well there's what Loppetve said, you can also do API calls and create your own portal / web gui. I know of one company that also does this,Abiquo; http://www.abiquo.com.
I know I've seen other's but I can't remember them at the moment.